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RELATED APPLICATIONS
This application is related to applications Ser. No. 323,138 filed Mar. 13,
1989, Ser. No. 323,126, filed Mar. 10, 1989, now U.S. Pat. No. 4,889,653,
Ser. No. 323,134, filed Mar. 13, 1989 and Ser. No. 323,137, filed Mar. 13,
1989 all of which are directed to aqueous automatic dishwasher detergent
compositions containing an anti-filming agent or an anti-filming and
anti-spotting agent.
FIELD OF THE INVENTION
The present invention relates to an automatic dishwasher detergent
composition having improved anti-filming and/or anti-spotting properties.
The present invention is particularly directed to a stable nonaqueous
liquid dishwasher detergent composition containing an anti-filming and/or
anti-spotting agent for use in an automatic dishwasher to clean dishware,
glassware and the like.
The present invention more particularly relates to a nonaqueous liquid
dishwashing detergent composition with improved anti-filming and
anti-spotting properties and to a method of using the detergent
composition to clean dishware, glassware, china and the like. The
dishwashing composition contains an anti-filming agent, or an anti-filming
agent and poly acrylic acid polymer or salt anti-spotting agent, inorganic
builder salts, bleach compound and detergent.
The detergent dishwashing composition of the present invention reduce
filming and/or spotting on dishware, glassware, china and the like,
particularly in hard water at low temperature.
More specifically, the invention relates to the use of a nonabrasive amount
of small substantially water insoluble silica particles, as an
anti-filming agent and polyacrylic acid or salt polymer as an
anti-spotting agent in nonaqueous liquid dishwashing detergent
compositions to reduce filming and/or spotting.
The detergent compositions do not require an added rinse aid, are stable in
storage and are readily dispersible in the wash bath.
The present invention specifically relates to nonaqueous liquid automatic
dishwashing detergent compositions having improved anti-filming
properties, which are readily dispersible in the washing medium to provide
effective cleaning of dishware, glassware, china and the like.
The present invention also relates to an improved nonaqueous liquid
composition and to a method of using the composition.
BRIEF DESCRIPTION OF THE INVENTION
The present invention is directed to a nonaqueous liquid automatic
dishwasher detergent composition having improved anti-filming and/or
anti-spotting properties for cleaning of dishware, glassware, china and
the like. The detergent composition contains as an essential ingredient a
nonabrasive amount of small substantially water insoluble silica, alumina
or titanium dioxide particles as an anti-filming agent. The compositions
can additionally contain a polyacrylic acid polymer or salt as an
anti-spotting agent.
The present invention specifically relates to nonaqueous liquid automatic
dishwashing detergent compositions having improved anti-filming and/or
anti-spotting properties for cleaning of dishware, glassware, china and
the like.
The nonaqueous liquid compositions are stable in storage, do not settle,
are readily pourable and are readily dispersed in water.
PRIOR ART
Commercially available household-machine dishwasher detergents provided in
powder or liquid form have many disadvantages. Commercially available
powder detergents have the disadvantages of non-uniform composition;
costly operations necessary in their manufacture; tendency to cake in
storage at high humidities, resulting in the formation of lumps which are
difficult to disperse; dustiness, a source of particular irritation to
users who suffer allergies; and tendency to cake in the dishwasher machine
dispenser.
In addition, the commercially available formulated powder detergents
frequently require a separate step of hand towel wiping and drying of the
dishware, glassware, china and the like to avoid leaving undesirable
traces or film. The use of liquid detergent compositions present other
problems. The builder salts settle in storage and are not readily
redispersed. The compositions also frequently become thicker in storage
and are not readily pourable.
For effective use, it is generally recommended that the automatic
dishwashing detergent, hereinafter also designated ADD, contain (1) sodium
tripolyphosphate (NaTPP) to soften or tie up hard-water minerals and to
emulsify and/or peptize soil; (2) sodium silicate to supply the alkalinity
necessary for effective detergency and to provide protection for dishware,
such as fine china and protection against machine corrosion; (3) sodium
carbonate, generally considered to be optional, to enhance alkalinity; (4)
a chlorine-releasing agent to aid in cleaning; (5) a surfactant and (6) a
defoamer to reduce foam, thereby enhancing machine efficiency. See, for
example, SDA Detergents in Depth, "Formulations Aspects Of Machine
Dishwashing," Thomas Oberle (1974). Cleansers approximating to the
afore-described compositions are mostly liquids or powders. Generally,
such compositions omit hypochlorite bleach, since it tends to react with
other chemically active ingredients, particularly surfactant, thereby
impairing its effectiveness.
U.S. Pat. No. 3,985,668 describes abrasive scouring cleaners of gel-like
consistency containing (1) suspending agent, preferably the Smectite and
attapulgite types of clay; (2) abrasive, e.g. silica sand or perlite; and
(3) filler comprising light density powdered polymers, expanded perlite
and the like. The perlite has a bouyancy and thus stabilizing effect on
the composition in addition to serving as a bulking agent, thereby
replacing water otherwise available for undesired supernatant layer
formation due to leaking and phase destabilization. The foregoing are the
essential ingredients. Optional ingredients include hypochlorite bleach,
bleach stable surfactant and buffer, e.g. silicates, carbonates, and
monophosphates. Builders, such as NaTPP, can be included as further
optional ingredients to supply or supplement building function not
provided by the buffer, the amount of such builder not exceeding 5% of the
total composition, according to the patent. Maintenance of the desired
(greater than) pH 10 levels is achieved by the buffer/builder components.
High pH is said to minimize decomposition of chlorine bleach and undesired
interaction between surfactant and bleach. When present, NaTPP is limited
to 5%, as stated. Foam killer is not disclosed.
U.S. Pat. No. 4,511,487 dated Apr. 16, 1985 describes a low-foaming
detergent paste for dishwashers. The composition is based on a mixture of
finely divided hydrated sodium metasilicate, an active chlorine compound
and a thickening agent which is a foliated silicate of the hectorite type.
Small amount of nonionic tensides and alkali metal carbonates and/or
hydroxides may be used.
The Laitem et al U.S. Pat. No. 4,753,748 discloses a nonaqueous liquid
automatic dishwashing detergent composition comprising a liquid nonionic
surfactant containing a stable or readily redispersible suspension of a
polyphosphate builder and/or citrate salt and an alkylene glycol mono
alkyl ether anti-gel agent.
Scott U.S. Pat. No. 4,438,014 discloses a powder formulation containing a
novel nonionic surfactant for automatic dishwasher detergent compositions.
The nonionic surfactant consists of an alkyl group to which there is
directly attached a propylene oxide polymer to which is attached an
ethylene oxide-propylene oxide random copolymer. The nonionic surfactant
is described as providing optimum cleaning and good spotting and film
results and good defoaming power.
ADVANTAGES OVER THE PRIOR ART
The nonaqueous liquid detergent compositions of the present invention
overcome many of the prior art problems associated with powder and liquid
detergents. Because of the addition of a small effective amount of a
silica, alumina or titanium dioxide anti-filming agent or silica and
polyacrylic acid polymer or salt anti-spotting agent to the composition an
added rinse aid is not required and towel wiping and drying are not
required to obtain dry sparkling clean dishes, glasses, cups and eating
utensils.
The nonaqueous liquid automatic dishwashing detergent compositions of the
present invention have the advantages of being stable, nonsettling in
storage, and non-gelling in storage, and are readily dispersible in the
dishwashing machine. The liquid compositions of the present invention are
easily pourable, easily measured and easily put into dishwashing machines.
Further, because the dishwashing machines as built and marketed have a
built in volume space in which the detergent is placed, the concentrated
nature of the liquid detergent concentrate composition of the present
invention allows placing in the dishwashing machine more active liquid
detergent, e.g. more dispersed polyphosphate and other detergent builders.
The nonaqueous liquid detergent compositions of the present invention with
the exception of the anti-film agent, are readily soluble in the wash
water in the dishwashing machine.
OBJECTS OF THE PRESENT INVENTION
It is an object of the present invention to provide a nonaqueous liquid
automatic dishwasher detergent composition that has improved anti-filming
and/or anti-spotting properties.
It is another object of the invention to provide a nonaqueous liquid
detergent composition which is stable in storage, does not degrade or
decompose, is easily pourable, is readily dispersible and is readily
soluble in the dishwashing water.
A further object of the invention is to provide a method of washing
dishware, glassware, china and the like in an automatic dishwashing
machine using a nonaqueous liquid detergent composition in which a
separate rinse aid is not added or needed.
A still further object of the invention is to provide a method of washing
dishware, glassware, china and the like in an automatic washing machine
using a nonaqueous liquid detergent composition by which method the
dishware, glassware, china and the like are machine dried with reduced
film and/or spots.
It is a further object of this invention to provide an improved nonaqueous
liquid detergent composition, especially an automatic dishwasher detergent
composition, by incorporating in the composition a small effective amount
of a silica anti-filming agent or silica and polyacrylic acid polymer or
salt as anti-filming and anti-spotting agents.
DETAILED DESCRIPTION OF THE INVENTION
These and other objects of the invention which will become more readily
understood from the following detailed description of the invention and
preferred embodiments thereof which are achieved by incorporating in a
nonaqueous liquid detergent composition a small but effective amount of a
silica, alumina or titanium dioxide anti-filming agent or silica
anti-filming agent and polyacrylic acid polymer or salt anti-spotting
agent. More particularly, in a preferred and specific embodiment of the
invention, there is provided a nonaqueous liquid automatic dishwasher
detergent composition in which is incorporated from about 0.5 to 10% of a
silica anti-filming agent or silica anti-filming agent and 1 to 30% of a
water soluble polyacrylic acid polymer or salt anti-spotting agent. The
silica anti-filming agent has a particle size of about 0.1 to 10 microns.
The water soluble polyacrylic acid or salt polymer has a molecular weight
of about 1000 to 100,000.
In accordance with the present invention there is provided a nonaqueous
liquid automatic dishwasher detergent composition which includes, on a
weight basis;
(a) 20 to 60% organic carrier liquid;
(b) 20 to 60% organic or inorganic builder salt;
(c) 5 to 30% sodium silicate;
(d) 3 to 15% peroxygen bleach compound;
(e) 0 to 8% bleach activator;
(f) 0.5 to 10% silica anti-filming agent;
(g) 0 to 30% polyacrylic acid polymer or salt;
(h) 0 to 25% alkali metal carbonate;
(i) 0.1 to 12% water dispersible organic detergent active material; and
(j) 0 to 6% foam depressant.
The present invention also provides a method for cleaning dishware,
glassware, china and the like in an automatic dishwashing machine with an
aqueous wash bath containing an effective amount of the nonaqueous liquid
automatic dishwasher detergent (LADD) composition as described above.
According to this aspect of the invention, the LADD composition is stable
in storage, is easily measured and can be readily poured into the
automatic dishwashing machine.
The invention will now be described in greater detail by way of specific
embodiments thereof.
In accordance with the present invention an improved automatic dishwasher
detergent composition is prepared by incorporating small amounts of a
silica anti-filming agent or silica anti-filming agent and polyacrylic
acid polymer or salt in a dishwasher composition.
The present invention is based upon the discovery that substantially
improved anti-filming and/or anti-spotting properties can be obtained by
adding to the nonaqueous liquid detergent composition a small effective
amount of a silica anti-filming agent or silica anti-filming agent and
polyacrylic acid polymer or salt anti-spotting agent.
In accordance with an embodiment of the present invention a nonaqueous
liquid automatic dishwashing detergent composition is prepared by
dispersing a polyphosphate builder in an organic carrier liquid. The
polyphosphate builder may be replaced in whole or in part by an organic
builder.
In addition other ingredients can be added to the composition such as
anti-encrustation agents, anti-foam agents, optical brighteners, enzymes
and perfume.
Organic Carrier Liquids
The organic carrier liquids that can be used in accordance with the present
invention are carrier liquids, diluents and solvents that are compatible
with the composition ingredients. Suitable organic carrier liquids are
polyethylene glycol M.W. 300, M.W. 400 and M.W. 4000, propylene glycol,
propylene carbonate, polypropylene glycol M.W. 200 and M.W. 300, methoxy
propylene glycol, Carbowax MPEG 350 (polyethylene glycol methyl ether),
from Union Carbide, triethanol amine, Butyl Carbitol, from DuPont Co,
Glyme (ethylene glycol dimethyl ether), Diglyme (diethylene glycol
dimethyl ether).
There can also be used as organic carrier liquids the alkylene glycol
monoalkyl ethers. The alkylene glycol mono alkyl ethers are low molecular
weight amphiphilic compounds, particularly a mono-, di- or tri lower
(C.sub.2 to C.sub.3) alkylene glycol mono lower (C.sub.1 to C.sub.5) alkyl
ether. Suitable examples of such additive amphiphilic compounds are
ethylene glycol monoethyl ether C.sub.2 H.sub.5 --O--CH.sub.2 CH.sub.2 OH,
diethylene glycol monobutyl ether C.sub.4 H.sub.9 --O--(CH.sub.2 CH.sub.2
O).sub.2 H and dipropylene glycol monomethyl ether
##STR1##
The above discussed organic carrier liquids can be used alone or in
admixture in order to obtain a desired viscosity and stability of the
product liquid.
The compositions of the present invention have good viscosity and stability
characteristics and remain stable and pourable at low temperatures.
Liquid Nonionic Surfactant Detergents
The liquid nonionic surfactant detergents that can be used in the practice
of the present invention are preferably the low foam poly-lower
alkoxylated lipophiles.
Useful nonionics are represented by the low foam Plurafac series from BASF
Chemical Company which are the reaction product of a higher linear alcohol
and a mixture of ethylene and propylene oxides, containing a mixed chain
of ethylene oxide and propylene oxide, terminated by a hydroxyl group.
Examples include a C.sub.13 -C.sub.15 fatty alcohol condensed with 6 moles
ethylene oxide and 3 moles propylene oxide, a C.sub.13 -C.sub.15 fatty
alcohol condensed with 7 moles propylene oxide and 4 moles ethylene oxide
and a C.sub.13 -C.sub.15 fatty alcohol condensed with 5 moles propylene
oxide and 10 moles ethylene oxide.
Other useful surfactants are Neodol 25-7 and Neodol 23-6.5, which products
are made by Shell Chemical Company, Inc. The former is a condensation
product of a mixture of higher fatty alcohols averaging about 12 to 15
carbon atoms, with about 7 moles of ethylene oxide and the latter is a
corresponding mixture wherein the carbon atom content of the higher fatty
alcohol is 12 to 13 and the number of ethylene oxide groups present
averages about 6.5. The higher alcohols are primary alkanols. Other
examples of such detergents include Tergitol 15-S-7 and Tergitol 15-S-9
(registered trademarks), both of which are linear secondary alcohol
ethoxylates made by Union Carbide Corp. The former is mixed ethoxylation
product of 11 to 15 carbon atoms linear secondary alkanol with seven moles
of ethylene oxide and the latter is a similar product but with nine moles
of ethylene oxide being reacted.
A nonionic surfactant that can be used is available from Union Carbide
Corporation under the trademark Tergitol MDS-42. This nonionic surfactant
is a C.sub.12 -C.sub.14 linear alcohol containing 55% by weight random
distributed oxyalkyl groups of which 42% are ethoxy and 58% propoxy
groups.
A preferred nonionic surfactant that can be used in accordance with the
present invention has the following formula
R-O-(PO).sub.x -(EO/PO)H
R is an alkyl group having 8 carbon atoms, PO is a propylene oxide polymer
attached directly to the oxygen of the alkyl group, x is 8 to 9, EO/PO
represents a copolymer of ethylene oxide and propylene oxide in which the
ethylene oxide and propylene oxide are randomly mixed. The molar ratio of
EO/PO is about 2:1 to 5:1, e.g. about 3:1. The total number of EO and PO
groups in the copolymer are such that the number of EO and PO groups are 5
to 8 and the cloud point of the nonionic surfactant is about 20.degree. to
30.degree. C.
A method of making the nonionic surfactant and a more complete description
of the nonionic surfactant is given in the Scott U.S. Pat. No. 4,438,014
which is incorporated herein in its entirety.
Other useful nonionic surfactants are the Poly-Tergent S-LF surfactants
available from Olin Corporation. These surfactants are low foaming,
biodegradable linear fatty alcohols. Surfactants of this type are
available under the tradenames Poly-Tergent S-LF 18, Poly-Tergent
S-305-LF, Poly-Tergent S-405-LF and Poly-Tergent CS-1.
Mixtures of two or more of the liquid nonionic surfactants can be used and
in some cases advantages can be obtained by the use of such mixtures.
In addition, the above discussed nonionic surfactants, anionic surfactants
can also be used.
Anionic Surfactants
The anionic surfactants that can be used are the linear or branched alkali
metal mono- and/or di-(C.sub.8-14) alkyl diphenyl oxide mono and/or
disulphonates, commercially available for example as DOWFAX (Registered
Trademark) 3B-2 and DOWFAX 2A-1.
Other suitable surfactants include the primary alkylsulphates,
alkylsulphonates, alkylaryl-sulphates and sec. alkylsulphates. Examples
include sodium C.sub.10-18 alkylsulphates such as sodium dodecylsulphate
and sodium tallow alcoholsulphate; sodium C.sub.10-18 alkanesulphonates
such as sodium hexadecyl-1-sulphonate and sodium C.sub.12-18
alkylbenzenesulphonates such as sodium dodecylbenzenesulphonates. The
corresponding potassium salts may also be employed.
Surfactants of the foregoing type, all well known in the art, are
described, for example, in U.S. Pat. Nos. 3,985,668 and 4,271,030, which
are incorporated herein by reference thereto.
The nonionic and anionic surfactants are used in amounts of 0.1 to 12%,
preferably 0.5 to 10.0%, and more preferably about 1.0 to 8.0%, for
example 2 to 7%.
ANTI-FILMING AGENTS
The anti-filming agent comprises a nonabrasive amount of small
substantially water insoluble silica particles. There can also be used as
anti-filming agents alumina and titanium dioxide particles. The
anti-filming agent accordingly can be a member selected from the group
consisting of silica, alumina and titanium dioxide and mixtures thereof.
Silica
The silica anti-filming agent materials that can be used are fumed or
precipitated synthetic or natural silica. The silica may be amorphous or
crystalline.
The silica material that is used may contain up to about 0.1 to 5% alumina
(Al.sub.2 O.sub.3), usually up to about 0.5 to 3% and more usually about
1% alumina, based on the weight of silica.
A preferred silica material is Syloid 244 which is amorphous silica, has a
particle size of about 4 microns and is provided by W. R. Grace Co.
Another suitable silica material is Silox 15, also from W. R. Grace Co.,
which has a particle size of about 4 microns.
Another preferred silica material is Huber Zeo 49 which is amorphous silica
and is provided by J. M. Huber Corporation and contains about 1% alumina
(Al.sub.2 O.sub.3).
The particle size of the silica material that is used is important in
achieving the desired anti-filming properties.
The silica particles that are used are finely divided and can have a
particle size of about 0.10 to 10 microns, preferably 0.50 to 8 microns
and more preferably about 1.0 to 5.0 microns. The silica particles of this
size and the amount used herein are not abrasive.
The finely divided silica material particles in the dishwashing wash act to
coagulate proteinaceous particulate soils and keeps them in suspension to
prevent them from depositing on the clean glass and dishware to form a
film.
Alumina
The alumina material that can be used as an anti-filming agent is
commercially available and is insoluble in water and has the formula
Al.sub.2 O.sub.3. Suitable materials are available under the tradenames
Alumina Oxide C, available from Degussa Company and Catapal D, available
from Vista Corp. Preferred alumina materials are fumed alumina and a
precipitated alumina.
Titanium Dioxide
The titanium dioxide material that can be used as an anti-filming agent is
insoluble in water and has the formula TiO.sub.2. Suitable materials are
available under the tradenames Titanium Dioxide P25, available from
Degussa Co. Preferred titanium dioxide materials are fumed titanium
dioxide and precipitated titanium dioxide.
The particle size of the alumina and titanium dioxide material that are
used is important in achieving the desired anti-filming properties.
The alumina or titanium dioxide particles that are used are finely divided
and can have a particle size of about 0.01 to 10 microns, preferably 0.01
to 8 microns and more preferably about 0.020 to 4.0 microns. For example,
a suitable particle size is about 0.01 to 0.50 microns. The alumina and
titanium dioxide particles of this size and in the amount used herein are
not abrasive.
The finely divided alumina or titanium dioxide material particles in the
dishwashing wash act to coagulate proteinaceous particulate soils and
keeps them in suspension to prevent them from depositing on the clean
glass and dishware.
Without intending to limit the invention in anyway it is theorized that the
alumina and titanium dioxide anti-filming agents function in the following
manner. The surface of vitreous glassware contains negatively charged
sites through the Si-O bonds. Usually the oxygen atoms carry these
charges. It is postulated that these negatively charged ions will attract
positively charged particles and thereby will form an "artificial soil"
layer. This protective mono-layer will then repel the regular food soil
and will increase the anti-redeposition property of the automatic
dishwashing detergent. The alumina and titanium dioxide particles,
respectively, will generate positively charged particles which will bond
themselves to the glassware surface to form the artificial soil layer
which will prevent the formation of film.
The amount of silica, alumina or titanium dioxide anti-filming agent that
can be used to achieve the desired improvement in film will depend on the
hardness of the water, detergent active compound, inorganic salts and
other ADD ingredients. The silica, alumina or titanium dioxide
anti-filming agents are particularly effective in hard wash water of, for
example, 300 ppm hardness or more.
The amount of each of the silica, alumina or titanium dioxide anti-film
agent that is used can be about 0.5 to 10%, preferably about 1 to 8% and
more preferably about 1.5 to 6% by weight based on the weight of the
entire composition.
The silica, alumina and titanium dioxide can each be used alone or one or
more of them can be used mixed together. When the anti-filming agents are
used mixed together the weight percent amounts mentioned above are the
total for the anti-film agent ingredients used in the mixture.
ANTI-SPOTTING AGENTS
Polyacrylic Acid Polymers And Salts Thereof
The polyacrylic acid polymers and salts thereof anti-spotting agents that
can be used are generally commercially available and are briefly described
as follows.
The polyacrylic acid polymers and salts thereof that can be used comprise
water soluble low molecular weight polymers having the formula
##STR2##
wherein the R.sub.1, R.sub.2 and R.sub.3 can be the same or different and
can be hydrogen, C.sub.1 -C.sub.4 lower alkyl, or combinations thereof.
The value of n is 5 to 1000, preferably, 10 to 500, and more preferably 20
to 100. M represents hydrogen, or an alkali metal such as sodium or
potassium. The preferred substituent for M is sodium.
The preferred R.sub.1, R.sub.2 and R.sub.3 groups are hydrogen, methyl,
ethyl and propyl. Preferred acrylic acid monomer is one where R.sub.1 to
R.sub.3 are hydrogen, e.g. acrylic acid, or where R.sub.1 and R.sub.3 are
hydrogen and R.sub.2 is methyl, e.g. methyl acrylic acid monomer.
The degree of polymerization, i.e. the value of n, is generally determined
by the limit compatible with the solubility of the polymer in water. The
terminal or end groups of the polymer are not critical and can be H, OH,
CH.sub.3 or a low molecular weight hydrocarbon.
The polyacrylic acid polymers and salts thereof can have a molecular weight
of 500 or 1,000 to 100,000, preferably 1,500 to 80,000 and especially
preferably 2,000 to 50,000.
Specific polyacrylic acid polymers which can be used include the Acrysol
LMW acrylic acid polymers from Rohm and Haas, such as the Acrysol LMW-45N,
a neutralized sodium salt, which has a molecular weight of about 4,500 and
Acrysol LMW-20NX, a neutralized sodium salt, which has a molecular weight
of about 2,000. Other polyacrylic acid polymers or salts thereof that can
be used are: Alcosperse 149, molecular weight 2000, Alcosperse 123,
molecular weight 4500, Alcosperse 107, molecular weight 3000, Alcosperse
124, molecular weight 2000, and Alcosperse 602N molecular weight 4500, all
of which are available from Alco Chemical Corp. The low molecular weight
acrylic acid polymers can, for example, have a molecular weight of about
1,000 to 10,000. Another polyacrylic acid polymer that can be used is
Alcosperse 110 (from Alco) which is a sodium salt of an organic
polycarboxylate and which has a molecular weight of about 100,000.
The above polyacrylic acid polymers and salts thereof can be made using
procedures known in the art, see for example U.S. Pat. No. 4,203,858.
The amount of polyacrylic acid polymer or salt that can be used to achieve
the desired improvement in anti-filming and anti-spotting properties will
depend on the hardness of the water, detergent active compound, inorganic
salts and other ADD ingredients.
The polyacrylic acid or salt anti-spotting agent is particularly effective
in reducing spotting in hard water of, for example, 300 ppm hardness or
more.
Generally, the amounts of the polyacrylic acid polymer or salt
anti-spotting agent that can be used are in the range of from about 1.0 to
30%, preferably from about 2.0 to 25%, especially preferably about 4 to
20%.
BUILDER SALTS
Generally, ADD effectiveness is related to (a) oxygen bleach levels; (b)
alkalinity; (c) solubility in washing medium; and (d) foam inhibition. It
is preferred herein that the pH of the aqueous wash bath after addition of
the liquid ADD composition be at least about 9.5, more preferably from
about 10.5 to 13.5 and most preferably at least about 11.5.
The amount of alkali metal silicate added and the amount of alkali metal
TPP added can be used to obtain the desired alkalinity in the wash bath.
The sodium carbonate can be added to act as a buffer to maintain the
desired pH level in the wash bath. The sodium carbonate can be added in an
amount of 0 to 25 wt. %, preferably 5 to 20 wt. % and typically about 5 to
15 wt. % of the detergent composition.
The compositions of the present invention can contain inorganic builder
salts such as NaTPP or organic builder salts such as the alkali metal
salts of polycarboxylic acids.
A preferred solid builder salt is an alkali metal polyphosphate such as
sodium tripolyphosphate (TPP). In place of all or part of the alkali metal
polyphosphate one or more other detergent builder salts can be used.
Suitable other builder salts are alkali metal borates, phosphates and
bicarbonates.
Specific examples of such builders are sodium tetraborate, sodium
pyrophosphate, potassium pyrophosphate, sodium bicarbonate, sodium
hexametaphosphate, sodium sesquicarbonate, sodium mono and
diorthophosphate, potassium bicarbonate and sodium or potassium zeolites.
The detergent builders, e.g. NaTPP may be employed in the nonaqueous liquid
ADD composition in a range of 20 to 60%, preferably about 20 to 55 wt. %,
and more preferably about 20 to 45 wt. %. The NaTPP may be anhydrous or
hydrated, including the stable hexahydrate with a degree of hydration of 6
corresponding to about 18% by weight of water or more. However, anhydrous
NaTPP is preferred.
The NaTPP may be replaced in whole or in part by organic builder salts.
Since the compositions of this invention are generally highly
concentrated, and, therefore, may be used at relatively low dosages, it is
desirable to supplement any phosphate builder (such as sodium
tripolyphosphate) with an auxiliary builder such as an alkali metal
polycarboxylic acid. Suitable alkali metal polycarboxylic acids are alkali
metal salts of citric and tartaric acid, e.g. monosodium and disodium
citrate (anhydrous). The sodium salts of citric and tartaric acids are
preferred.
Foam Inhibitors
Foam inhibition is important to increase dishwasher machine efficiency and
minimize destabilizing effects which might occur due to the presence of
excess foam within the washer during use. Foam may be sufficiently reduced
by suitable selection of the type and/or amount of detergent active
material, the main foam-producing component. The degree of foam is also
somewhat dependent on the hardness of the wash water in the machine
whereby suitable adjustment of the proportions of NaTPP which has a water
softening effect may aid in providing the desired degree of foam
inhibition. However, it is generally preferred to include a foam
depressant or inhibitor. Particularly effective are the alkyl phosphonic
acid esters of the formula
##STR3##
available, for example, from BASF-Wyandotte (PCUK-PAE), and especially the
alkyl acid phosphate esters of the formula
##STR4##
available, for example, from Hooker (SAP) and Knapsack (LPKN-158), in
which one or both R groups in each type of ester may represent
independently a C.sub.12-20 alkyl group. Mixtures of the two types or
mixtures of mono- and di-esters of the same type, may be employed.
Especially preferred is a mixture of mono- and di-C.sub.16-18 alkyl acid
phosphate esters such as monostearyl/distearyl acid phosphates 1.2/1
(Knapsack). When employed, proportions of 0.01 to 6 wt. %, preferably 0.1
to 5 wt. %, especially about 0.5 to 4.5 wt. %, of foam depressant in the
composition is typical, the weight ratio of detergent active component to
foam depressant generally ranging from about 10:1 to 1:1 and preferably
about 4:1 to 1:1. Other defoamers which may be used include, for example,
the known silicones, such as Dow Corning 1400 and 1500, which are
polysiloxanes mixed with dispersed silica.
Bleaching Agents
The peroxygen bleach compounds are preferrably used in the compositions of
the present invention. The oxygen bleaches are well known and are
represented by percompounds which liberate hydrogen peroxide in solution.
Preferred examples include sodium and potassium perborates, percarbonates,
and perphosphates, and potassium monopersulfate. The perborates,
particularly sodium perborate monohydrate, are preferred. The peroxygen
compounds can be used in an amount of 3 to 15, preferably 4 to 12 and more
preferably 4 to 8% by weight.
The peroxygen compound is preferably used in admixture with an activator
therefor. Suitable activators which can lower the effective operating
temperature of the peroxide bleaching agent are used. Polyacylated
compounds are preferred activators; among these, compounds such as
tetraacetyl ethylene diamine (TAED) and pentaacetyl glucose are
particularly preferred. The bleach activators can be used in an amount of
0 to 8, preferably 1 to 8 and more preferably 2 to 6 wt. percent, for
example 2 to 4 wt. percent.
The bleach activators interact with the peroxygen compounds to form a
peroxyacid bleaching agent in the wash water.
Other useful activators include, for example, acetylsalicylic acid
derivatives, ethylidene benzoate acetate and its salts, ethylidene
carboxylate acetate and its salts, alkyl and alkenyl succinic anhydride,
tetraacetylglycouril (TAGU), and the derivatives of these.
The conventionally used dishwasher detergent composition chlorine bleach
compounds such as dichloro-isocyanurate, alkali metal, e.g. potassium and
sodium, hypochlorite should not be used because they are unstable in the
organic carrier liquids used in the compositions of the present invention.
That is compounds that contain hypochlorite or that generate hypochlorite
in the product liquid should not be used. Compounds that are stable in the
product liquid, but that develop hypochlorite ion in the dishwasher water
can however be used. For example, a combination of sodium chloride and
Oxone (TM for potassium mono persulfate) which develop hypochlorite ion in
the dishwasher water can be used.
Sodium Silicate
The sodium silicate, which provides alkalinity and protection of hard
surfaces, such as fine china, is employed in an amount ranging from about
5 to 30 wt. %, preferably about 7 to 26 wt. %, and more preferably about 8
to 24 wt. %, in the composition. For example the composition can contain 8
to 15% sodium silicate. The sodium silicate also protects the washing
machine from corrosion. The sodium silicate can have a Na.sub.2
O:SiO.sub.2 ratio of 1.6/1 to 1/3.2. The sodium silicate can be added in
the form of a dry powder or as a nonaqueous dispersion, preferably having
an Na.sub.2 O:SiO.sub.2 ratio of from 1/1 to 1/2.8, for example, 1/2.4.
Potassium silicates of the same ratios can also be used. The preferred
alkali metal silicates are anhydrous sodium disilicate and sodium
metasilicate.
Most of the other components of the composition, for example, foam
depressant can be added in the form of dry powders or nonaqueous
dispersions or solutions.
The detergent active materials used in the present invention can be either
the nonionic or anionic detergents. The nonionic detergents are, however,
preferred.
Various conventional ingredients may be included in these compositions in
small amounts, generally less than about 4 wt. %, e.g. 0.5 to 4% such as
perfume, hydrotropic agents such as the sodium benzene, toluene, xylene
and cumene sulphonates, preservatives, dyestuffs and pigments and the
like. Especially preferred for coloring are the chlorinated
phthalocyanines and polysulphides of aluminosilicate which provide,
respectively, pleasing green and blue tints.
The nonaqueous liquid ADD compositions of this invention are readily
employed in known manner for washing dishes, glasses, cups, eating
utensils and the like in an aqueous wash bath, in an automatic dishwasher,
containing an effective amount of the composition.
The composition may also include conventional organic or inorganic
thickening agents in amounts sufficient to obtain a product consistency of
a cream or a paste.
The thickening agents, i.e. thickeners or suspending agents which provide
thickening properties, are known in the art and may be organic or
inorganic, water soluble or insoluble, dispersible or colloid-forming, and
monomeric or polymeric, and should of course be stable in these
compositions, e.g. stable to alkalinity. The preferred thickeners
generally comprise the inorganic, colloid-forming clays of smectite and/or
attapulgite types. These materials are generally used in amounts of about
1.5 to 10, preferably 2 to 5 wt %, to confer the desired thickening
properties to the formulation.
Smectite clays include montmorillonite (bentonite), hectorite, attapulgite,
smectite, saponite, and the like. Montmorillonite clays are preferred and
are available under tradenames such as Thixogel (Registered Trademark) No.
1 and Gelwhite (Registered Trademark) GP, H, etc., from Georgia Kaolin
Company; and ECCAGUM | | |
