Technical Field
[0001] The present invention relates to general purpose, hard surface, liquid cleaning compositions
comprising nonionic surfactants and polymeric components.
Background of the Invention
[0002] Compositions for cleaning hard surfaces generally comprise one or more nonionic surfactants
as cleaning agents involved in the removal of soil from the surface. Nonionic surfactants
have far better fatty soil detergency than charged surfactants and are typically used
in general purpose cleaning compositions for hard surfaces such as kitchen worktops,
bathroom fittings, floors and the like.
[0003] A broad range of nonionic surfactants are known and used in cleaning compositions.
For example, these surfactants typically comprise alkoxylated alcohols described as
compounds produced by the condensation of alkylene oxide groups, which are hydrophilic
in nature, with an organic hydrophobic compound which may be aliphatic or alkyl aromatic
in nature. The length of the hydrophilic or polyoxyalkylene radical which is condensed
with any particular hydrophobic group can be readily adjusted to yield a water-soluble
compound having the desired degree of balance between hydrophilic and hydrophobic
elements. Particular examples include the condensation product of aliphatic alcohols
having from 8 to 22 carbon atoms in either straight or branched chain configuration
with ethylene oxide, such as a coconut oil ethylene oxide condensate having from 2
to 15 moles of ethylene oxide per mole of coconut alcohol; alternatives include condensates
of alkylphenols whose alkyl group contains from 6 to 12 carbon atoms with 5 to 25
moles of ethylene oxide per mole of alkylphenol.
[0004] It is known to incorporate components into a nonionic surfactant-based composition
with the intention that deposition of such components onto surfaces will provide a
protective layer against soiling in a one step cleaning operation. Our published application
WO 94/26858 discloses how certain anionic polymers can be used, together with nonionic
surfactants, both to improve initial cleaning and to prevent soil redeposition on
hard surfaces which have been cleaned with compositions comprising these polymers.
It is believed that the polymer not only improves the initial detergency of the formulation
but is also deposited on the surface during the cleaning process, leaving a protective
film which either prevents soil adhesion or assists in soil removal. In addition to
the anionic polymers it is known to deposit silicone materials and fluorosurfactants
so as to achieve the same end.
[0005] WO 94/26858 discloses how cleaning compositions which deposit a protective film of
polymer may be prepared at acid pH's. As is noted in WO 94/26858, the benefit of these
polymers was lost as the pH of the prior products was increased. Furthermore, one
recognised difficulty with acid products is that they have the potential to damage
certain surfaces, particularly enamels such as those used on baths. It is also preferred
that cleaning compositions should be formulated at high pH so as to give particularly
good fatty soil detergency. It is therefore desirable to be able to formulate products
across the entire pH range 3-11 while maintaining the soil release and low effort
cleaning benefits outlined in the above mentioned case.
[0006] WO 89/12673 discloses liquid fabric cleaning compositions comprising nonionic and
cationic surfactants and polyacrylate builder. The pH of the compositions is 7.5-12
or 3-5. Although the mol weight of the polymers is not specified, it is known that
polyacrylate builders have mol weights well below 100,000, see e.g. US 3,922,230 and
US 4,797,223.
Brief Description of the Invention
[0007] We have now determined that the presence of cationic surfactant enables the pH of
nonionic and polymer containing products to be increased, without the loss of the
benefits due to polymers. While it is believed that this enables the difficulties
associated with low pH formulations to be overcome the incorporation of cationic surfactants
has additional advantages as set out below.
[0008] Accordingly the invention provides a hard surface cleaning composition of pH 3-12
comprising:
a) 1-30% nonionic surfactant,
b) 0.005-5% of a water soluble, anionic polymer having an average molecular weight
of above 100,000 and less than 1000000, said polymer being free of quaternary nitrogen
groups, wherein, the ratio of polymer:nonionic is 0.1:1 or less, and,
c) 0.005-5% of a cationic surfactant.
[0009] A further aspect of the present invention relates to a method for cleaning hard surfaces
which comprises the step of treating the surface with a cleaning composition of pH
3-12 comprising:
a) 1-30% nonionic surfactant,
b) 0.005-5% of a water soluble, anionic polymer having an average molecular weight
of above 100,000 and less than 1000000, said polymer being free of quaternary nitrogen
groups, wherein, the ratio of polymer:nonionic is 0.1:1 or less, and,
c) 0.005-5% of a cationic surfactant.
[0010] Without wishing to limit the present invention by reference to any theory of operation
it is believed that enhanced detergency of nonionic surfactants, at acid pH, in the
presence of polymer is due to the formation of a hydrogen bonded complex between the
nonionic surfactant and the uncharged, undissociated carboxylic acid groups of the
polymer. As the pH is raised, the acid groups of the polymer dissociate and the hydrogen-bonded
complex is no longer formed. It is believed that in the presence of the cationic surfactant
required by the present invention, negatively charged (i.e. carboxylic dissociated)
polymer can interact with the cationic surfactant and the nonionic surfactant to form
a three-component complex which deposit the nonionic surfactant upon the soil and/or
surface being cleaned. While the mechanism is not entirely clear, this may possibly
be due to the interaction of the charged polymer with mixed miscelles of cationic
and nonionic surfactant.
[0011] It is believed that the deposition of the complex on the surface has two results.
Firstly the concentration of the surfactant at the surface is increased, resulting
in improved cleaning in the initial cleaning cycle and a reduction in the so-called
primary cleaning effort. It is also believed that the complex, or at least some part
of it, remains on the surface after cleaning and prevents or reduces the reattachment
of soil to the surface thereby making the surface easier to clean in second and subsequent
cleaning cycles, i.e. it reduces the 'secondary' cleaning effort.
[0012] The presence of a cationic surfactant in the compositions of the invention can also
provide an antimicrobial effect during primary cleaning where the cationic is antimicrobial.
Using compositions according to the invention it is possible to achieve a log 5 reduction
in populations of bacteria. Surprisingly, we have determined that compositions according
to the invention which contain antimicrobial cationic surfactants show longer lasting
hygiene on surfaces which have been treated with the compositions and can maintain
the antimicrobial effect even after the surfaces have been rinsed. This is believed
to be due in part to the retention of antimicrobial components of the formulation
at the surface and may be due in part to the formulation preventing re-adhesion of
microbes on the surface.
[0013] Accordingly, a third aspect of the present invention relates to the use, in a surface
cleaning composition comprising nonionic surfactant and an antimicrobial cationic
surfactant, of a water soluble, anionic polymer having an average molecular weight
of above 100,000 and less than 1000,000, said polymer being free of quaternary nitrogen
groups, to prolong the antimicrobial effectiveness of the antimicrobial cationic surfactant
on said surface.
[0014] As will be explained in further detail below, the compositions of the invention can
comprise other benefit components which become deposited at the surface during a cleaning
operation performed with such a composition.
Detailed Description of the Invention
[0015] Various preferred and essential features of the invention are described in further
detail below.
Polymers
[0016] The water soluble polymer is an essential component of the compositions according
to the present invention.
[0017] As noted above the polymers according to the invention are water soluble polymers
having an average molecular weight of above 100,000 and less than 1000,000, and being
free of quaternary nitrogen groups. Typically, these polymers are polymers bearing
carboxylate functional groups although the use of other anionic polymers is not excluded.
In the context of the present invention, anionic polymers are those which carry a
negative charge or similar polymers in protonated form. Mixtures of polymers can be
employed.
[0018] The preferred polymers in embodiments of the present invention are those which are
readily available in the marketplace. These are polymers of acrylic or methacrylic
acid or maleic anhydride, or a co-polymer of one or more of the same either together
or with other monomers.
[0019] Particularly suitable polymers include polyacrylic acid, polymaleic anhydride and
copolymers of either of the aforementioned with ethylene, styrene and methyl vinyl
ether.
[0020] The most preferred polymers are maleic anhydride co-polymers, preferably those formed
with styrene, acrylic acid, methyl vinyl ether and ethylene.
[0021] The molecular weight of the polymer is in excess of 100,000. VERSICOL E-11 [RTM]
(ex. Allied Colloids) which is a polyacrylic acid, has been found to be a suitable
polymer for use in compositions according to the invention.
[0022] Typically, the surfactant based cleaning compositions comprise at least 0.01wt% polymer,
on product. The positive benefit of the presence of polymer as regards the improvement
in cleaning properties can be identified even when very low levels of polymer and
surfactant are present. This property of a low concentration threshold is particularly
advantageous in applications of the invention where considerable dilution is expected,
such as in floor cleaning.
[0023] Preferably the level of polymer is 0.05-5.0wt% at which level the anti-resoiling
benefits become particularly significant. More preferably 0.2-2.0wt% of polymer is
present. We have determined that higher levels of polymer do not give significant
further cleaning advantages with common dilution factors, while increasing the cost
of compositions. It is believed that high levels of polymer increase the viscosity
of the product and hinder product wetting and penetration of the soil. However, for
concentrated products which are significantly diluted prior to use, the initial polymer
level can be as high as 5%wt.
[0024] As mentioned above, the molecular weight of the polymer is below 1 000 000 Dalton.
It is believed that as the molecular weight increases the cleaning benefit of the
polymer is reduced.
Surfactants
[0025] It is essential that compositions according to the present invention comprise at
least one nonionic surfactant.
The composition according to the invention comprise detergent actives which can be
chosen from commercially available nonionic detergent actives. Suitable nonionic detergent
active compounds can be broadly described as compounds produced by the condensation
of alkylene oxide groups, which are hydrophilic in nature, with an organic hydrophobic
compound which may be aliphatic or alkyl aromatic in nature. Alkoxylated alkanols
are particularly preferred.
[0026] The length of the hydrophilic or polyoxyalkylene radical which is condensed with
any particular hydrophobic group can be readily adjusted to yield a water-soluble
compound having the desired degree of balance between hydrophilic and hydrophobic
elements. In general, the compounds will be alkoxylated alcohols having C8-C22 alkyl
chains and 1-20 molar equivalents of ethylene oxide and/or propylene oxide residues
attached thereto.
[0027] Particular examples include the condensation product of aliphatic alcohols having
from 8 to 18 carbon atoms in either straight or branched chain configuration with
2-15 moles of ethylene oxide. Examples of such materials include a coconut oil ethylene
oxide condensate having from 2 to 15 moles of ethylene oxide per mole of coconut alcohol;
condensates of alkylphenols whose alkyl group contains from 6 to 12 carbon atoms with
5 to 25 moles of ethylene oxide per mole of alkylphenol.
[0028] The preferred nonionic surfactants are the condensation products of 9-15 carbon alcohols
with 3-10 moles of ethylene oxide. In embodiments of the invention we have found that
DOBANOL [RTM] series ethoxylated alcohol nonionic surfactants (ex. Shell) are suitable.
Preferred materials include DOBANOL 91-5 [TM] (C9-C11 alkyl, 5 EO alkyl ethoxylate
ex. Shell) and DOBANOL 91-8 [TM] (C9-C11 alkyl, 8 EO alkyl ethoxylate ex. Shell).
[0029] It is possible to use mixtures of nonionic surfactants. As will be described in more
detail below these mixed systems have some advantages in antifoaming the products.
[0030] Alternative nonionic surfactant materials which are envisaged include condensates
of the reaction product of ethylenediamine and propylene oxide with ethylene oxide,
the condensates containing from 40 to 80% of polyoxyethylene radicals by weight and
having a molecular weight of from 5,000 to 11,000; tertiary amine oxides of structure
R
3NO, where one group R is an alkyl group of 8 to 18 carbon atoms and the others are
each methyl, ethyl or hydroxy-ethyl groups, for instance dimethyldodecylamine oxide;
tertiary phosphine oxides of structure R
3PO, where one group R is an alkyl group of from 10 to 18 carbon atoms, and the others
are each alkyl or hydroxyalkyl groups of 1 to 3 carbon atoms, for instance dimethyldodecylphosphine
oxide; and dialkyl sulphoxides of structure R
2SO where the group R is an alkyl group of from 10 to 18 carbon atoms and the other
is methyl or ethyl, for instance methyltetradecyl sulphoxide; fatty acid alkylolamides;
alkylene oxide condensates of fatty acid alkylolamides and alkyl mercaptans. In addition,
it is believed that alkyl polyglycoside surfactants can be employed as the nonionic
surfactant.
[0031] The amount of nonionic detergent active to be employed in the composition of the
invention will be from 1 to 30%wt, preferably from 3 to 15%wt. Levels of above 15%
active show little increase in neat-use cleaning performance, although such higher
levels can be employed in products intended to be considerably diluted prior to use.
Typical compositions will comprise 5-10%wt nonionic active on product. Anionic surfactant
can be present in relatively small proportions, however it is preferable that anionic
surfactant is absent from composition. As described in further detail below small
amounts of anionic detergents may be present in the form of soaps as part of an antifoam
system. It is preferred that the compositions of the invention comprise less than
2%wt, preferably less than 1% of anionic surfactant.
[0032] Typically the cationic surfactants are materials of the general formula R
1R
2R
3R
4N
+X
-, wherein all of the radicals are hydrocarbons with or without hydroxy substitution,
at least one of the radicals R1-R4 is a C6-C22 alkyl, alkaryl or hydroxyalkyl, at
least one of the radicals R1-R4 is a C1-C4 alkyl or hydroxy alkyl and X is a monovalent
anion equivalent.
[0033] The cationic surfactants are preferably, quaternary nitrogen compounds of the general
formula R
1R
2R
3R
4N
+X
-, where R1 and R2 are the same or different C1-C4 alkyl or hydroxy alkyl, R3 is a
C6-C22 alkyl, alkaryl or hydroxyalkyl, R4 is a C1-C22 alkyl, alkaryl or hydroxyalkyl
and X is a monovalent anion equivalent.
[0034] Preferably X is a halogen, most preferably chloride or bromide.
[0035] Preferably R1 and R2 are methyl. In embodiments of the invention R3 is preferably
C8-C18 alkyl, more preferably C10-C16 alkyl. In embodiments of the invention R4 is
preferably methyl, C8-C18 alkyl or benzyl. Thus, the cationic surfactants used can
have three 'short chain' radicals such as methyl and one fatty-soluble 'long chain'
radical or two 'short' chains and two fatty-soluble 'long chains', wherein the 'long
chains' can be either linear or branched hydrocarbons or contain aromatic rings.
[0036] A further advantage of including a cationic surfactant in the compositions of the
invention is that preferred cationic surfactants confer antimicrobial properties on
the formulation. Surprisingly, we have determined that compositions according to the
invention which contain antimicrobial cationic surfactants show longer lasting hygiene
on surfaces which have been treated with the compositions.
[0037] Particularly suitable cationic detergent-active compounds include cetyltrimethyl
ammonium bromide (CTAB), hardened ditallow di-methyl ammonium chloride (available
in the marketplace as BARDAC 2250), benzalkonium chloride and mixtures thereof.
[0038] The cationic surfactants which comprise one aryl substituent are especially preferred
as they are believed to give particularly good antimicrobial effects.
[0039] Typical levels of cationic surfactant will lie in the range of 0.05-3%wt on product.
Preferred levels of cationic surfactant are around 1-3%wt.
[0040] The total amount of detergent active compound to be employed in the detergent composition
of the invention will generally be from 1.5 to 30%, preferably from 2 to 20% by weight,
most preferably from 5-20wt%.
Solvents
[0041] Solvents may be present in the compositions of the invention.
[0042] It is preferred that the compositions of the present invention comprise not more
than 2%wt of solvents of the general formula:
R
1-O-(EO)
m-(PO)
n-R
2,
wherein R
1 and R
2 are independently C2-6 alkyl or H, but not both hydrogen, m and n are independently
0-5. It is believed that the use of polymers in compositions according to the present
invention can offset the otherwise deleterious effects of any solvent which is present
when the product is used on certain plastics materials.
[0043] More preferably, no more than 2%wt of solvent selected from the group comprising
di-ethylene glycol mono n-butyl ether, mono-ethylene glycol mono n-butyl ether, propylene
glycol n-butyl ether and mixtures thereof is present. Advantageously, effectively
no solvent other than water is present.
Metal ion binding agents
[0044] Preferably the composition contain either detergent builders or non-building metal
ion sequesterants, collectively these are known as metal ion binding agents.
[0045] Suitable metal ion binding agents include nitrilotriacetates, polycarboxylates, citrates,
dicarboxylic acids, water-soluble phosphates especially polyphosphates, mixtures of
ortho- and pyrophosphate, zeolites and mixtures thereof. Such agents can additionally
function as abrasives if present in an amount in excess of their solubility in water
as explained herein. In general, where the metal ion binding agent is a builder it
will preferably will form from 0.05 to 25% by weight of the composition.
[0046] Metal ion binding agents such as ethylenediaminetetraacetates (e.g. EDTA), amino-polyphosphonates
(e.g. those available as the 'DEQUEST' (TM) series of materials) and phosphates and
a wide variety of other poly-functional organic acids and salts (including materials
such as methyl glycine diacetate (MGDA)), can also optionally be employed.
[0047] A particular, further advantage of including metal ion binding agents, preferably
organic acetates, more preferably MGDA or EDTA is believed to be that the microbiocidal
properties of the cationic surfactants are improved especially against Gram-negative
bacteria particularly under hard water conditions.
[0048] Preferred levels of metal ion binding agents are 0.05-5%wt, preferably 0.1-3.0%wt,
most preferably 1.5-3%wt. In preferred compositions containing around 2% cationic
surfactant, 1.5-3% of an organic acetate sequesterant will give a log five reduction
in viable bacteria even against recalcitrant bacterial strains such as
Pseudomomas aeruginosa.
[0049] Preferred compositions according to the invention contain 1.5-3%wt of MGDA or EDTA.
[0050] In addition to the cleaning benefit we have determined that the formulation containing
polymer, alcohol, ethoxylate, cationic surfactant and sequestering agent has the additional
benefit that it reduces the adhesion of fungal and/or bacterial spores to surfaces.
This is described in further detail below with reference to examples.
Minors
[0051] The composition according to the invention can contain other ingredients which aid
in their cleaning performance and general utility.
[0052] Typically, a further optional ingredient for compositions according to the invention
is a suds regulating material, which can be employed in compositions according to
the invention which have a tendency to produce excessive suds in use. One example
of a suds regulating material is soap. Soaps are salts of fatty acids and include
alkali metal soaps such as the sodium, potassium, ammonium and alkanol ammonium salts
of higher fatty acids containing from about 8 to about 24 carbon atoms, and preferably
from about 10 to about 20 carbon atoms. Particularly useful are the sodium and potassium
and mono-, di- and triethanolamine salts of the mixtures of fatty acids derived from
coconut oil and ground nut oil. When employed, the amount of soap can form at least
0.005%, preferably 0.5% to 2% by weight of the composition.
[0053] Further example of a suds regulating materials are organic solvents, hydrophobic
silicas, silicone oils and hydrocarbons.
[0054] An a ternative suds regulating material comprises a mixed EO/PO nonionic surfactant.
Suitable ethoxylated/propoxylated nonionic detergents include the condensation product
of aliphatic alcohols having from 8 to 22 carbon atoms in either straight or branched
chain configuration with ethylene oxide and propylene oxide, such as a coconut oil
ethylene oxide/propylene oxide condensate having from 2 to 15 moles in total of ethylene
oxide and propylene oxide per mole of coconut alcohol. It is preferable that the mole
ratio of ethylene oxide to propylene oxide lies in the range 1:5-5:1.
[0055] Particularly preferred ethoxylated/propoxylated nonionics include molecules of the
general formula:
R(EO)
n(PO)
mH
wherein: R is an alkyl residue having an average carbon chain length of C8-C14, preferably
C9-C11, EO is an ethylene oxide residue, n is 1-10, PO is a propylene oxide residue
and m is 1-5. A particularly preferred material is C9-11 5-8EO 1-3PO, most preferably
C9-11 6EO 2PO.
[0056] The amount of ethoxylated/propoxylated nonionic detergent active to be employed in
the composition of the invention will generally be from 2 to 10%wt, and most preferably
from 3-6%wt.
[0057] Preferred ratios of the ethoxylated to the ethoxylated/propoxylated surfactant fall
into the range 4:1-2:1 with the ethoxylated surfactant being present in weight excess
over the ethoxylated/ propoxylated surfactant.
[0058] Compositions according to the invention can also contain, in addition to the ingredients
already mentioned, other optional ingredients such as pH regulants, sunscreens, colourants,
optical brighteners, soil suspending agents, enzymes, compatible bleaching agents,
gel-control agents, freeze-thaw stabilisers, additional biocides, preservatives, detergent
hydrotropes, perfumes and opacifiers.
[0059] Hydrotropes, are useful optional components. It is believed that the use of hydrotropes
enables the cloud point of the compositions to be raised without requiring the addition
of anionic surfactants.
[0060] Suitable hydrotropes include, alkali metal toluene sulphonates, urea, alkali metal
xylene and cumene sulphonates, short chain, preferably C
2-C
5 alcohols and glycols. Preferred amongst these hydrotropes are the sulphonates, particularly
the cumene and toluene sulphonates.
[0061] Typical levels of hydrotrope range from 0-5% for the sulphonates. Correspondingly
higher levels of urea and alcohols are required. Hydrotropes are not generally required
for dilute products.
[0062] Given that the compositions of the invention effectively comprise a means for deposition
of a surfactant/polymer complex at the surface being cleaned, it is envisaged that
the compositions of the invention can further comprise components which it is desirable
to deposit upon a surface. Three preferred classes of additional components are perfumes,
non-cationic surfactant antimicrobial components and insect repellents and/or insecticides.
[0063] Given that the compositions of the invention already comprise a cationic surfactant
and are alkaline, some antimicrobial activity is already found in the compositions.
Suitable additional non-cationic non-surfactant antimicrobial components are known
in the art. Typical examples of this class of materials includes antimicrobial perfume
oils and oil components.
[0064] Typical levels of the non-cationic antimicrobial agent in formulations range from
0.01 to 8%, with levels of 0.05-4wt%, particularly around 2% being preferred for normal
compositions and up to two or four times that concentration being present in so called,
concentrated products. For sprayable products the concentration of the antimicrobial
agent will be in the range 0.05-0.5%wt.
[0065] Particularly suitable insect repellents include essential oils such as those of genus
Mentha, particularly Mentha arvensis, mentha piperita, Mentha spicata and Mentha cardica;
Lemongrass East Indian oil, Lemon oil, Citronella, Cedarwood and Pine oil; terpenoids,
particularly limonene, carvone, cineole, linalool, Gum Camphor, citronellal, alpha
and beta terpenol, fencholic acid, borneol, iso borneol, bornyl acetate and iso bornyl
acetate. The most preferred insect repellants are the terpenoids, particularly limonene.
Of the above-mentioned oils many are known to show antimicrobial effects as well as
being insect repellents and/or perfumes.
[0066] The level of insect repellent required will vary with the nature of the material
used. For essential oils and terpenoids, preferred levels are 0.1-5% on product.
[0067] It is preferable that the compositions of the present invention are essentially free
of abrasive particles.
[0068] The preferred pH of the neat products is 7-12 with a pH in the range of 7-11 being
more preferred and a pH of around 10-11 being particularly preferred so as to balance
cleaning and hygiene effectiveness.
[0069] Particularly preferred compositions according to the present invention are mobile
aqueous liquids, having a pH of 7-12 (preferably 7-11) which comprise:
a) 5-20%wt of a ethoxylated, 2-15EO, C8-C18 alcohol, nonionic surfactant,
b) less than 1%wt of anionic surfactants,
c) 0.2-2%wt of a water soluble, anionic polymer having an average molecular weight
of above 100,000 and less than 1,000,000, said polymer being a polymer of at least
one of acrylic acid, methacrylic acid or maleic anhydride, with at least one of acrylic
acid, methacrylic acid, maleic anhydride, ethylene, styrene and methyl vinyl ether,
and ,
d) 0.05-5%wt (preferably 0.05-2%wt) of a cationic surfactant which is a quaternary
nitrogen compounds of the general formula R1R2R3R4N+X-, where R1 and R2 are the same or different C1-C4 alkyl or hydroxy alkyl, R3 is a
C6-C22 alkyl, alkaryl or hydroxyalkyl, R4 is a C1-C22 alkyl, alkaryl or hydroxyalkyl
and X is a monovalent anion equivalent, and,
e) not more than 2% of a solvent selected from the group comprising di-ethylene glycol
mono n-butyl ether, mono-ethylene glycol mono n-butyl ether, propylene glycol n-butyl
ether and mixtures thereof.
[0070] More particularly preferred compositions according to the invention are as described
in the above paragraph but contain a cationic surfactant which has antimicrobial properties
(such as benzalconium chloride) and a metal ion bing agent which is an organic acetate.
These compositions exhibit improved primary and secondary cleaning at high pH as well
as having effective and persistent antimicrobial properties against a broad range
of microbes.
[0071] Compositions can be manufactured which comprise an essentially dry powder and which
form the compositions of the invention on the addition of water.
[0072] In order that the present invention may be further understood it will be described
hereafter by way of the following nonlimiting examples.
EXAMPLES
Examples 1-6: primary end secondary cleaning
[0073] In all the cleaning examples described below a specified level (based on non-volatiles)
of soil were deposited on an 'A4' sized area of 'DECAMEL' (RTM ex Formica) test surface
by spraying. The soil comprised 1% glycerol tripalmitate, 0.5% glycerol trioleate,
0.5% kaolin, 0.2% liquid paraffin, 0.1% palmitic acid, 0.02% carbon black in methylated
spirits. The soil was allowed to age for a specified time at room temperature prior
to cleaning. The initial effort required to clean the surface is referred to below
as the primary cleaning effort.
[0074] Where secondary cleaning benefits were examined, in order to investigate the anti-resoiling
performance, the DECAMEL sheets were pretreated with the test composition and copiously
rinsed prior to soiling. The effort required to clean the re-soiled surfaces is known
as the secondary cleaning effort.
[0075] In both primary and secondary cleaning the total effort used to remove the soil from
the test surface using a cellulosic sponge cloth was measured using a rig fitted with
force measuring means to determine the total effort applied to the surface. Due to
variability in the experimental conditions, in the data which follows results should
not be compared between series of experiments presented in different tables.
[0076] Formulations comprised nonionic surfactant and water with and without polymer and
with and without cationic surfactant.
The nonionic surfactants employed were DOBANOL 91-5 [TM] (C9-C11 alkyl, 5 EO alkyl
ethoxylate ex. Shell) and DOBANOL 91-8 [TM] (C9-C11 alkyl, 8 EO alkyl ethoxylate ex.
Shell). The polymers illustrative of the present invention were a polyacrylic acid
(VERSICOL E11 [TM] ex Allied Colloids) which had an average molecular weight of 250,000
Daltons. The cationic surfactants used were C
n-alkyl trimethyl ammonium bromide (C
nTAB: where n is 12,14 and 16), dicetyldimethyl and tricetylmethyl ammonium bromides
(DTAB and TTAB respectively). The pH of the compositions was regulated with sodium
hydroxide or a carbonate/bicarbonate buffer system as indicated.
[0077] Example 1a-1d in Table 1 below show the primary cleaning effort required using compositions
which contained the formulations given, on the soil given above, aged for a period
of two days after application of the soil at a coverage of 0.5mg/cm
2.
Table 1
|
1a |
1b |
1c |
1d |
|
Dobanol 91-5 |
7% |
7% |
7% |
7% |
Cetyl TAB |
- |
- |
1% |
1% |
Versicol E11 |
- |
0.5% |
- |
0.5% |
Carbonate/bicarbonate |
pH9 |
pH9 |
pH9 |
pH9 |
Cleaning Effort (N/s) |
1036 |
769 |
689 |
412 |
[0078] From table 1 it can be seen that the primary cleaning effort is minimised at alkaline
pH in the presence of both the cationic surfactant and the polymer (example 1d), while
higher effort is required if either or both of these components is absent (compare
with comparative examples 1a, 1b and 1c). It is believed that this is due to the formation
of a polymer/surfactant complex which increases the surfactant concentration at the
surface.
[0079] Table 2 below shows the effect of the cationic type on primary cleaning effort. Experiments
were performed on the soil given above aged for a period of one day after application
of the soil at a coverage of 0.25mg/cm
2.
[0080] From table 2 it can be seen that compared with the control (comparative example 2a)
primary cleaning effort is in all cases markedly reduced by the combination of surfactant,
polymer and cationic (examples 2d, 2f and 2h) as compared with systems in which only
the cationic is added (comparative examples 2c, 2e and 2g). Addition of the polymer
alone, in the absence of the cationic surfactant, (comparative example 2b) gives no
significant reduction in primary cleaning effort at this pH. It can be seen that of
the different cationics used the TTAB and CTAB materials give the lowest cleaning
effort.
[0081] Table 3 below further illustrates the effect of pH for compositions which comprise
7% Dobanol 91-5 and 0.5% Versicol E11 in the presence of differing levels of CTAB
at the pH indicated. pH was regulated with hydroxide and the experiments were performed
on the soil given above aged for a period of one day after application of the soil
at a coverage of 0.25mg/cm
2. Results are given in total primary effort to clean in N/s.
Table 3
|
3a |
3b |
3c |
|
pH |
pH6 |
pH8 |
pH10 |
0% CTAB |
213 |
262 |
- |
25% CTAB |
163 |
195 |
193 |
0.5% CTAB |
142 |
180 |
175 |
1% CTAB |
151 |
131 |
190 |
[0082] From Table 3 it can be seen that through this pH range the primary cleaning effort
generally falls as the level of the cationic surfactant level is increased.
[0083] Table 4 below provides additional data on the effect of pH for compositions which
comprise 8% active in total and 0.5% Versicol E1 in the presence of differing levels
of CTAB (C) and DTAB (D) at the pH indicated. The non-cationic active material is
Dobanol 91-5. pH was regulated with hydroxide and the experiments were performed on
the soil given above aged for a period of one day after application of the soil at
a coverage of 0.25mg/cm
2. Results are given in total primary cleaning effort in N/s.
Table 4
|
4a |
4b |
4c |
4d |
|
pH |
pH4 |
pH7 |
pH4 |
pH7 |
type of cationic |
C |
C |
D |
D |
|
0.00% cationic |
162 |
749 |
162 |
749 |
0.13% cationic |
171 |
399 |
171 |
308 |
0.25% cationic |
188 |
288 |
173 |
227 |
0.50% cationic |
190 |
403 |
162 |
269 |
[0084] From Table 4 it can be seen that compositions show poor cleaning performance at the
higher pH unless the cationic surfactant is present. In the lower pH range (examples
4a and 4c) the effect disclosed in WO 94/26858 is believed to be acting to reduce
the primary cleaning effort requirement and there is no significant effect of adding
cationic (if anything the compositions get slightly worse) although useful cleaning
results are still attained.
[0085] In the higher pH range (examples 4b and 4d) it can be seen that the addition of cationic
surfactant significantly lowers the cleaning effort and enables the nonionic/polymer
systems to achieve similar results to those obtained in more acidic products.
[0086] Table 5 below show the effect on the primary cleaning energy effort requirement and
the cloud point of modifying the nonionic surfactant present. The compositions comprise
7% of a mixture of Dobanol 91-5 and Dobanol 91-8, 1% CTAB and 0.5% Versicol E11. The
table lists the percentage of Dobanol 91-8 in the nonionic portion of the surfactant
mixture, the remainder of the mixture being the Dobanol 91-5.
Table 5
|
% Dobanol 91-8 |
Effort (N/s) |
Cloud Point |
|
5a |
0 |
331 |
30 |
5b |
25 |
401 |
42.5 |
5c |
50 |
479 |
53 |
5d |
75 |
809 |
64 |
5e |
100 |
876 |
75 |
[0087] From Table 5 it can be seen that the compositions which are rich in the Dobanol 91-5
surfactant (for example 5a) give the best reduction in primary cleaning effort, whereas
while the compositions which are rich in Dobanol 91-8 (for example 5e) also give a
useful reduction in primary cleaning effort this is less marked than for the other
surfactant. It is clear from the table that the selection of an appropriate combination
of surfactants enables the cloud point of the compositions to be controlled.
[0088] Table 6 below shows the effect on the secondary cleaning effort requirement in subsequent
cleaning cycles for the compositions of the invention, using two different cationics.
The 'VARI' material is Varisoft 442-100P (TM: ex. Sherex-Witco) a dihardened tallow
dimethyl ammonium chloride.
Table 6
|
6a |
6b |
6c |
6d |
|
CTAB |
CTAB |
VARI |
VARI |
|
primary |
resoiled |
primary |
resoiled |
|
pH6 |
886 |
203 |
846 |
364 |
pH8 |
679 |
257 |
745 |
460 |
pH10 |
969 |
426 |
958 |
602 |
pH12 |
637 |
211 |
501 |
408 |
[0089] From Table 6 it can be seen that in all cases the surfaces proved more easy to clean
in the second cleaning cycle (compare 6a with 6b and compare 6c with 6d). It is believed
that this demonstrates that the one or more components of the composition are being
deposited on the surface and leaving a residual film which either retards the attachment
of soil or aids in its removal, i.e. the secondary cleaning effort after re-soiling
of the surfaces is reduced.
[0090] The above examples illustrate how the compositions of the present invention enable
a reduction of both primary and secondary cleaning effort over a broad pH range.
Example 7-9: Biocidal effects
[0091] Table 7: below shows the result of a biocidal efficacy test using the following bacteria
(from the National Collection of Type Cultures or American Type Culture Collection).
Cultures were maintained on beads in a cryopreservative at -80/C.
Staphylococcus aureus |
NCTC 10788 |
Pseudomomas aeruginosa |
ATCC 15442 |
Saccharomyces cerevisiae |
ATCC 9763 |
[0092] To prepare inocculum a bead was removed from the storage vial and aseptically transferred
to 100ml Nutrient Broth and incubated at 37/C in a shaking waterbath for 24 hours
(bacteria). After incubation, the culture suspensions were aseptically transferred
into two 50ml centrifuge tubes and centrifuged at 2180g for 10 minutes (Mistral 1000,
MSE) in order to harvest the cells. The supernatants were poured off and the pellets
resuspended in peptone diluent (0.1 percent peptone and 0.85 percent sodium chloride,
pH 7.0). The suspensions were kept at 4/C until needed, and before use in the test
were left on the bench at ambient temperature for at least 30 minutes.
[0093] The test used was a microtitre plate assay, which is comparable to
'Method for the test for the antimicrobial activity of disinfectants in food hygiene', more commonly known as the European Suspension Test (EST). Bovine albumin at a
low level (0.03 percent) or a high level (0.3 percent) was included in some of the
tests. A 1/15 dilution of the formulation was made in 'Water of Standard Hardness'
as referred to in the above method.
[0094] Microtitre plates (Bibby Sterilin, sterile 96-well, flat-bottom) were prepared by
adding 270ml quenching solution in row B of each plate and 270ml peptone diluent into
rows C-G. The quench solution was composed of Tween 80 (3.0 percent), lecithin (0.3
percent), L-histidine (0.1 percent), sodium thiosulphate (0.5 percent) and 0.25N KH
2PO
4 buffer (1 percent) in sterile distilled water (1 litre). Sterile distilled water
or bovine albumin as appropriate (120ml) was added to the test wells of row A. Then
the formulation (150ml 1/15 dilution) was added to the appropriate test wells. The
formulations were randomised across the plates. The plates were placed on a stainless
steel 'plate incubator' tray attached to a circulating waterbath, held at 20/C.
[0095] An aliquot of microbial suspension (30ml) was then added simultaneously to all the
wells of row A of the microtitre plate using a multichannel pipette. The test mixture
was left at 20/C for a contact time of 5 minutes ± 5 seconds, after which time an
aliquot (30ml) was transferred into row B (quench), giving a 10
-1 dilution. After 5 ± 1 min, an aliquot (30ml) was transferred to row C (peptone diluent).
Further serial dilutions were performed in the same manner until row G (10
-6 dilution). The bacteria were enumerated using the Miles-Misra technique. Three aliquots
(10ml) from each dilution were spotted onto pre-dried Tryptone Soya Agar plates which
had been divided into 6 sectors. The spots were allowed to dry and the plates incubated
at 37/C for 24 hours. Plates were counted by selecting a dilution segment with 3-50
cfu per spot and the average of the 3 spots was calculated. The decadic logarithm
of this number was calculated and subtracted from the decadic logarithm of the initial
count to give the log (reduction).
[0096] All formulations contained Dobanol 91-8 (8 percent) and polymer (polyacrylic acid
0.5wt percent), and were adjusted to pH9. Formulations were diluted 1/30 in test in
presence of WSH (water of standard hardness) and soil (bovine albumin). Examples are
provided both for formulations containing CTAB and benzalkonium chloride.
Table 7
ORGANISM |
CTAB (%) |
BAAC (%) |
MEAN LOG (REDUCTION) (2 replicates) |
|
|
|
LOW SOIL |
HIGH SOIL |
Staph. aureus |
1.0 |
- |
4.5 |
4.7 |
2.0 |
- |
7.4 |
7.6 |
- |
1.0 |
7.2 |
7.2 |
- |
2.0 |
7.2 |
7.2 |
Pseudomonas aeruginosa |
1.0 |
- |
0.1 |
0.03 |
2.0 |
- |
0.04 |
0.01 |
- |
1.0 |
2.3 |
2.6 |
- |
2.0 |
3.5 |
3.1 |
Saccharomyces cerevisiae |
1.0 |
- |
4.4 |
3.5 |
2.0 |
- |
7.0 |
2.7 |
- |
1.0 |
6.0 |
6.0 |
- |
2.0 |
6.0 |
6.0 |
[0097] From the results given in Table 7 it can be seen that the levels of cationic used
in the compositions of the present invention are sufficient to give a biocidal effect.
It can also be seen that benzalkonium chloride has an improved biocidal effect even
against the normally recalcitrant
Pseudomonas aeruginosa.
[0098] In order to show the effect of sequesterant in improving bacterial kill, formulations
were prepared which contained Dobanol 91-8 (7wt percent) and polymer (VERSICOL E11
polyacrylic acid 0.5wt percent), and were adjusted to pH11. Formulations were diluted
1/20 in the presence of WSH (water of standard hardness) and 0.03% soil (bovine albumin)
on final suspension. Examples are provided for formulations containing benzalkonium
chloride (BAC) at both 1.0 and 2.0 wt%. Sequesterant, either EDTA or MGDA was used
as indicated in table 8. The test bacteria was
Pseudomonas aeruginosa ATCC 15442, and assays were conducted as described above. Examples which give a log
reduction greater than 5 are indicated in bold.
Table 8
BAC % |
EDTA % |
MGDA % |
Log Reduction |
1 |
0.5 |
0 |
1.22 |
1 |
1 |
0 |
1.1 |
1 |
1.5 |
0 |
5.54 |
1 |
2 |
0 |
5.66 |
1 |
2.5 |
0 |
5.66 |
2 |
0.5 |
0 |
1.86 |
2 |
1 |
0 |
2.17 |
2 |
1.5 |
0 |
5.66 |
2 |
2 |
0 |
5.3 |
2 |
2.5 |
0 |
5.66 |
1 |
0 |
0.5 |
0.89 |
1 |
0 |
1 |
1.23 |
1 |
0 |
1.5 |
1.44 |
1 |
0 |
2 |
4.57 |
1 |
0 |
2.5 |
5.42 |
2 |
0 |
0.5 |
1.7 |
2 |
0 |
1 |
2.95 |
2 |
0 |
1.5 |
3.46 |
2 |
0 |
2 |
5.48 |
2 |
0 |
2.5 |
5.74 |
[0099] The results given in Table 8 show that a log five reduction in viable counts can
be obtained by use of appropriate levels of sequestering agents.
[0100] In order to demonstrate the advantages of longer lasting hygiene which accrue with
the compositions of the present invention, formulations were prepared which contained
Dobanol 91-8 (7wt percent) with and without polymer (VERSICOL E11 polyacrylic acid
0.5wt percent), and were adjusted to pH11. Formulations were diluted 1/20 in the presence
of WSH (water of standard hardness) and 0.03% soil (bovine albumin) on final suspension.
Examples are provided for formulations containing benzalkonium chloride (BAAC) at
both 1.5 and 2.0 wt%. Sequesterant, either EDTA or MGDA was used as indicated in table
9.
[0101] Efficacy was determined against
Staphylococcus aureus NCTC 6538 by means of the method set out below.
[0102] Glazed ceramic tiles squares (size = 2.5x2.5cm, were cut from plain black glazed
Cristal (TM) tiles, ex H & R Johnson with all sloping edges removed. The tiles were
cleaned rigorously before application of the test solution or product, so that a uniform
coverage on a hydrophilic surface is obtained. Cleaning is undertaken on the day that
application of product, and rinsing is carried out no longer than 24 hrs before microbiological
testing is undertaken. Tiles were cleaned by applying calcite powder to the tile and
rubbing vigorously with a clean, damp sponge cloth. Tiles are rinsed with de-ionised
water and it was determined if the tile was hydrophilic all over by allowing a small
amount of water to run over it. The water should run smoothly over the tile and form
an even film over the entire surface. If any area remained hydrophobic calcite was
reapplied and the cleaning process repeated. After cleaning, tiles were dried by wiping
with a clean paper tissue (Kimsoft (TM) facial tissue).
[0103] 50µl of cleaning product (whether a formulation according to the invention, a control
or a comparative example) was placed on a clean tile and carefully spread it over
the whole tile surface using a flattened micropipette tip. The tile was allowed to
dry in a 30°C incubator then any rinses were carried out by placing each tile in 100ml
of sterile WSH for 30 seconds, removing and placing in a 30°C incubator to dry.
[0104] After treatment with the products according to the invention, comparative examples
or controls the tiles were stored in a microbiological safety cabinet to limit contamination.
[0105] In order to demonstrated the substantive antibacterial effect, each product was tested
in duplicate, using 50µl of sterile distilled water as the control formulation for
control tiles. At time zero tiles treated according to the present invention were
inoculated together with a control tile with 20µl of culture (as described above)
so that there were approximately 2x10
7 bacteria/tile in a 0.03% Bovine Albumin soil. The bacteria were spread over the whole
tile area using a sterile spreader. After 30 minutes contact time between the bacteria
and the tiles, a sterile microbiological cotton swab was wet with quench solution
and swabbed thoroughly over the tile in two directions at right angles to each other.
The end off the swab was broken off into 10ml of quench solution and the process repeated
with a dry swab to remove residual liquid and bacteria. Quench bottles were left for
30 minutes to allow for recovery of injured cells (60 minutes for
E. coli). After recovery each quench bottle was vortexed for 15 seconds at high speed to
resuspend the cells evenly in the quench solution.
[0106] For each tile being tested, a column of wells in a sterile microtitre plate was inoculated
with 270µl of Peptone water, leaving the first well empty in each case. The first
well was filled with 300µl of the quenched swab solutions. A further 500µl of quenched
swab solution was plated directly onto an agar plate and spread using a sterile spreader.
This plate is used for enumerating low levels of survivors. Serial 10-fold dilutions
of the solutions were prepared by transferring 30µl of solutions in row 1 to row 2;
mixing them, then repeating the procedure down to row 6 so that a 10-6 dilution is
achieved (pipette tips are changed between transfers).
[0107] For each tile sample taken an agar plate (dried plate face down with the lid off
in a 60°C oven for 15 minutes prior to use and marked into 6 equal segments on its
base with a marker pen) was spotted with 10µl volumes of liquid onto the appropriate
segment of the plate, placing 3 spots per segment. All plates were left face up to
dry and then placed face down in an incubator at 37°C for 24 hrs. Counts were obtained
for the plates and log10 reduction obtained by subtracting the log10 count[test] from
log10 count[control].
[0108] Results for such a test are shown in table 9 below: all composition contained soil
and nonionic surfactant as noted above and the other components of the neat cleaning
composition are indicated in the table. As noted above, log reductions are calculated
relative to controls which had been treated with sterile water rather than a 'cleaning'
composition.
Table 9
Example |
BAAC% |
Polymer% |
EDTA% |
MGDA% |
Log Red Rinsed |
Log Red. Unrinsed |
9a |
1.5 |
0.5 |
- |
2.5 |
1.41 |
3.49 |
9b |
1.5 |
- |
- |
2.5 |
1.01 |
4.02 |
9c |
1.5 |
0.5 |
1.5 |
- |
1.80 |
3.87 |
9d |
1.5 |
- |
1.5 |
- |
0.35 |
4.02 |
9e |
2.0 |
0.5 |
- |
2.5 |
2.18 |
4.02 |
9f |
2.0 |
- |
- |
2.5 |
0.38 |
4.02 |
9g |
2.0 |
0.5 |
1.5 |
- |
2.67 |
4.02 |
9h |
2.0 |
- |
1.5 |
- |
0.01 |
2.48 |
[0109] From the results in table 9 it can be seen that bacteria recovered from a surface
which had been previously treated with a composition according to the invention (9a,
9c, 9f or 9h) had a significantly reduced viability of between 2-4 logs when the surface
was not rinsed. This reduction in viability would be expected given that the surfaces
had been exposed to a biocide-containing solution which had been allowed to dry on
the surface.
[0110] For the tiles which had been rinsed, only those treated with formulations which contained
polymer (9a, 9c, 9e and 9g) showed markedly better than 1 log reduction (90%) of the
recovered bacteria. Formulations using 2%wt BAAC, polymer and sequesterant (9e and
9g) showed the best results in the example with a better than 99% reduction in viable
count.
[0111] It is believed that these results show that the compositions of the invention have
a persistent antimicrobial effect as compared with the polymer free control compositions.
Example 10: Fungal Spore Adhesion
[0112] Plastic Petri dishes (9cm diameter, 2cm depth) were treated with 20ml of test product
at the recommended dilution (1:20, 30 min, room temperature), before decanting the
solution and allowing plates to dry. Control plates were untreated. Prior to dilution
the example formulation (10a) contained Dobanol 91-8 (7%wt) with polymer (VERSICOL
E11 polyacrylic acid 0.5%wt), cationic surfactant (2%wt BAAC) and sequesterant (2.5%wt
MGDA) and was adjusted to pH11 with NaOH. Comparative examples were also performed
against Lysoform (TM) a commercially available disinfectant product.
[0113] A suspension of
Aspergillus niger spores (ATCC 6275), prepared in sterile distilled water, was introduced to the plates
(20ml per plate, 3 x 10
5 spores/ml). Plates were agitated in an orbital shaker to distribute spores evenly
(1 min, 100 rpm) and left standing at room temperature for 30 min, before re-agitating
(1 min, 100 rpm). Supernatants were discarded and the plates allowed to dry. As the
plates had been allowed to dry after pretreatment and prior to exposure to the spores,
the spores had not been exposed to relatively high levels of the pre-treatment compositions.
Initial attachment of spores to the treated and untreated plates could then be determined
by the method given below.
[0114] To show the effect of rinsing, duplicate dishes which had been treated as above (including
the exposure to mould spores) were subjected to rinsing by introducing standard hard
water (10ml) into each dish and mixing (1 min, 100rpm).
[0115] The supernatant was discarded and the plates dried at room temperature.
[0116] To show the effect of scrubbing duplicate dishes which had been inoculated with spores
as described above were scrubbed using an epicyclic scrubbing device. Scrubbing of
the surface was achieved through the use of standard, pre-washed sponge cloths, dampened
with standard hard water, at a fixed pressure of 80g/cm
2, (10 cycles, speed 4). Dishes were then allowed to dry at room temperature as before.
[0117] Each of the above plates was viewed under light microscopy (x40 magnification) and
the average number of attached spores determined from each of five pre-defined fields
of view. Plates from the rinsing and scrubbing experiments were re-counted and the
numbers of spores recorded. The percentage attachment following each of the treatments
was calculated by the equation:
[0118] Results are given in table 10 below, a percentage of spores attached as compared
with an untreated surface
Table 10
|
Initial Attachment |
Attachment after rinsing |
Attachment after scrubbing |
10a |
45.05 |
32.67 |
5.41 |
Lysoform (TM) |
64.26 |
53.07 |
14.74 |
Control |
100.00 |
77.53 |
38.83 |
[0119] As expected, the results show that for untreated surfaces rinsing and scrubbing remove
some mould spores, but leave almost 40% of the spores on the surface even after scrubbing.
The results show that spores are less likely to attach to a surface treated with the
compositions of the present invention, and, when spores do attach, they are not as
strongly bound to the surface.
[0120] Statistical analysis of the data showed a significant decrease (95% confidence) in
the percentage of spores which attached to the surface in the presence of the polymer-containing
formulation, compared to the reference product Lysoform (RTM) and as compared with
untreated surfaces. As noted above, this difference was seen at each stage of treatment.
[0121] It is believed that these results show that the compositions of the invention at
least partly prevent the adhesion of spores to a surface and consequently, it is believed
that the use of a composition according to the present invention would reduce the
rate of regrowth on a clean surface of micro-organisms including moulds or bacteria
which propogate through spores.