[0001] The present invention relates to an improved automatic dishwashing detergent powder
with superior performance solubility, pourability, handling and storage characteristics
and method for making and using same.
BACKGROUND OF THE INVENTION AND PRIOR ART
[0002] In general automatic dishwashing detergent powders contain water soluble builder
salt, water-soluble silicate, bleach, preferably a water-soluble chlorine bleaching
agent, and water-soluble detergent which is usually an organic, low-foaming (i.e.
low "sudsing") non-ionic. For best cleaning efficiency and anti-corrosion effects,
the compositions are usually formulated with alkaline salts (i.e. sodium and potassium).
In the normal environment in the dishwashing machine, the automatic dishwashing compositions
generally yield a pH in the range of about 9.0 to 12.0 and more generally about 9.5
to 11.5. The alkaline builder salts which have been used are both of the inorganic
type (e.g. pyrophosphates; carbonates, silicates and so forth) and of the organic
type e.g. aminocarboxylates such as trisodium nitrilotriacetate, tetrasodium ethylene
diamine tetra-acetate, sodium citrate, sodium itaconate, sodium polymaleate, sodium
inter polymaleates, such as maleicacrylic (or vinyl) interpolymers, sodium oxydisuccinate
and so forth.
[0003] The builder generally function to increase the cleaning action of the composition
by supplying alkalinity and also by removing (i.e. "sequestering") ions which affect
the action and efficiency of the organic detergent.
[0004] The silicates which have been used are those wherein the Na₂O:SiO₂ ratio varies from
2:1 to 1:4 and more generally from about 1:1 to about 1:3.4, typically 1:1, 1:2 and
1:2.4.
[0005] The bleach employed is generally a chlorine-yielding agent and has been used in varying
amounts but generally to give available chlorine levels of from about 0.3% to about
10% and, more often, levels of about 1% to 5%. Typical bleaches are the inorganic
types such as sodium, lithium and calcium hypochlorite, and chlorinated trisodium
phosphate, as well as the organic forms such as the di- and tri- chlorocyanuric acids
and their alkali (e.g. sodium and potassium) metal salts, N-chloracetyl urea, 1,3-dichloro-5,5-dimethylkydantion,
etc.
[0006] The nonionic detergents in common usage have been any of the conventional hydrophobe
moieties (e.g. C₈ to C₂₀ alcohols, phenols, amides, acids, etc.) reacted with ethylene
oxide (or mixtures with other oxyalkylating agents such as propylene oxide or butylene
oxide). Typical nonionics used have been n-dodecanol with 10 moles of ethylene oxide;
tetradecyl alcohol-hexadecyl alcohol (1:1 weight ratio) with 5, 10, 15 or 20 moles
of ethylene oxide; polyoxypropylenes condensed (i.e. terminated) with oxyethylene
groups and having the general formula HO(C₂H₄O)
x(C₃H₆O)
y(C₂H₄O) H wherein y = 5 to 100 and typically 10 or 15 and x may be from about 5 to
several hundred e.g. 10, 20, 40, 50, etc. Among the latter type of nonionics have
been those where the oxyethylene component comprises from about 15% to 90% on a weight
basis of the non-ionic. Types of non-ionic detergent disclosed as generally useful
in automatic dishwashing compositions can be found in U.S. Patents 3314891, 3359207,
2677700, 2979528, 3036118, 3382176, 4115308 and 4411810. It has been known and generally
described that non-ionic surfactants even though a preferred class of detergents because
of their low-foam characteristics, are not, generally, considered "bleach-stable"
detergents and where the latter is of importance use of anionic surfactant, albeit
higher foamers, has been reported. Illustrative and a discussion of this problem
can be found in U.S. Patents 4116849, 5005027 and 4235732.
[0007] Automatic dishwashing detergents have been provided in two basic forms, as powders
and as "liquids" (or semi-liquids or pastes). The powders represent the "first generation".
They are simple to formulate, easy to dispense from machines which have, in the main
, been designed to handle powders and not liquids; and because of the presence of
the formulation "actives" in solid state, (and usually the components comprise separate
and discrete particles), there is a minimum of interaction among the composition
ingredients. "Liquids," the so-called "second generation" of products in this area
, on the other hand, are more convenient to dispense from the package; also they are
generally more soluble in water and therefore have less tendency to remain and/or
leave residues in the machine dispenser cup. Phase separation leading to decreased
homogeneity and an exacerbation of component interaction are among some of the minuses
of the liquid system. Some of the U.S. Patents mentioned earlier are specifically
directed to "liquid" systems.
BRIEF DESCRIPTION OF THE INVENTION
[0008] The present invention relates to an improved automatic dishwashing detergent in
powder form which is highly efficacious, has superior stability, is phase stable and
homogeneous and notwithstanding its powder characteristic has many of the advantages
of the liquid systems i.e. dispensibility, pourability and solubility without, however,
the problems and disadvantages often attending the use of liquid automatic dishwashing
compositions.
[0009] The compositions of this invention comprise builder salt, generally alkaline builder
salt, alkali-metal silicate, non-ionic surfactant and as a preferred optional ingredient,
bleaching agent. The product is characterized by a base bead of builder salt having
absorbed thereon the nonionic surfactant, said bead being admixed with the silicate
and bleach (where used). Where other optional materials are used they, too, are conveniently
post blended with the base beads. These materials may be alkali salts including builder
salts anti-oxidants, dyes, pigments, fragrances, anti-foamers, fillers, sequestering
agents, soil suspending agents, drainage improvers and the like.
DETAILED DESCRIPTION OF THE INVENTION
[0010] The present invention relates to an improved and superior automatic dishwahing detergent
composition in powder form which is free flowing, non-caking, homogeneous, highly
soluble and very low, if not entirely free of insolubles and residue when in use,
and methods for making and using such compositions.
[0011] The outstanding automatic dishwashing compositions which are provided are powders
and comprise a base material on which is absorbed or "loaded" a detergent, and in
admixture therewith an alkaline silicate and any other desired components. Of particular
value is a bleaching agent and alkaline reacting compounds such as alkali carbonates,
bicarbonates, borates, hydroxides and so forth.
[0012] The base material which is the carrier for the surfactant is a spray-dried phosphate
composition which also contains a small amount of a polymeric substance.
[0013] The spray-dried base is generally characterized as a "base bead" although it may
not necessarily be a bead in the usual geometric form. The absorbent base material
is comprised of a major portion of inorganic salts and generally and preferably phosphate
material. Suitable phosphates include trisodium phosphate, sodium tripolyphosphate,
monobasic sodium phosphate, dibasic sodium phosphate, dibasic sodium pyrophosphate,
tetra sodium pyrophosphate, sodium hexametaphosphate and the like. The corresponding
potassium salts along with mixtures of sodium and potassium salts are useful. It may
be desirable to add other salts to the phosphate such as the alkali metal carbonates,
bicarbonates, borates and silicates. The alkaline earth salts (e.g. calcium, magnesium,
etc.) of the non-phosphate inorganics may be used if desired and/or indicated. In
general, the base "bead" is prepared by spray-drying a slurry of the phosphate-containing
composition. The processing of slurries and spray-drying them to form base beads is
described in U.S. Patent 441429 to David Joshi and the entire disclosure of this patent
is incorporated herein by reference thereto.
[0014] The base material will generally comprise from about 50 to 95% alkali-metal polyphosphate.
On an anhydrous basis, the base may comprise from about 50% to 99% of inorganic salts
and again, preferably alkali metal polyphosphate. Minor amounts of moisture are almost
invariable present and the water content may vary from a few or less percent (e.g.
0.5%, 1%, 2%, 3%) to 20% & more but more generally from about 5% to 15%, typically
6%, 8%, 10% and 12%.
[0015] Other alkaline salts, particularly sodium carbonate, sodium tetraborate and sodium
silicate may be admixed with the phosphate in the crutcher before spray-drying. Generally
these materials are used in less than major amounts, generally from very small amounts
e.g. 1%, 2%, 5%, up to larger quantities, typically 10%, 15%, 20%, 30%, 35% & 40%.
Where silicate is used in the crutcher mix it is usually one of lesser alkalinity
e.g. Na₂O:SiO₂ ratio of about 1:1.6 to 1:3.4 typically 1:2.4.
[0016] A second essential component of the base bead is a water-soluble polymeric material
such as sodium polyacrylate, which is the most preferred polymer salt. Other water-soluble
polymers (at least soluble in such salt form) as poly (hydroxy) aerylates, copolymers
and inter polymers of acrylic acid with other copolymerizable monomers (usually B-olefinically
unsaturated) such as vinyl pyrrolidone, vinyl acetate, hydrolized polyvinyl acetate
(75-95% polyvinyl alcohol), acrylamide, methyl vinyl ether and so forth can be used.
Other polymers include water-soluble forms of starch and cellulose and particularly
derivatives such as sodium carboxy methylcellulose and the like. Natural proteins
are useful, too; examples include gelatin and the like. In general, the useful materials
are characterized by water-solubility and compatibility to form a base carrier suitable
for loading the detergent in quantities from 1 to about 10% and where described up
to quantities of 25-35%. Such polymers are useful in amounts of from about 0.5% to
about 10% and preferably from about 1% to 8%. Typical usage would be 1.5%, 2%, 2.5%,
3%, and 4%, especially with sodium polyacrylate. The molecular weights of the synthetic
polymers may vary from several hundred to several million, e.g. 600; 1200; 2000; 5000;
150,000; 500,000; 1,000,000; 5,000,000 and the like.
[0017] After the based bead has been prepared, it is used as an absorbent or carrier for
the detergent. The latter are preferably non-ionic surfactants which, in liquid form
are sprayed on to the base beads. The more desirable non-ionic detergent materials
are generally pasty to waxy at room temperature or at least sprayable as a liquid
at somewhat elevated temperatures e.g. 30°C, 40°C, 60°C, 80°C and 100°C.
[0018] The nonionic detergent materials comprise any of the class designated as nonionic
and generally comprises the oxyalhylated derivatives (preferably oxyethyl or mixed
oxpropyl-oxyethyl) of hydrophobic base moieties of about C₈ to C₃₀ carbon content
of such functional types as alcohols, thioalcohols, esters, acids and amides. The
preferred compounds are oxyethylated and mixed oxypropylated-oxyethylated aliphatic
alcohols of C₁₀ to C₁₈.
[0019] The non-ionic detergents are the preferred types because of their physical characteristics;
liquifiable and sprayable as well as low foaming; one of the major characteristics
of a detergent which adversely affects the cleaning efficacy of the dishwashing composition
is a high level of foam. This is due primarily to the fact that the cleaning action
is proportional to the force of the jets of water impinging on the dishes, etc., and
high levels of foam and thick or dence foam reduce this force and thusly the cleaning
action.
[0020] A general formula for the preferred non-ionics is:

wherein R = hydrogen or C₁₀ to C₁₈ alkyl and preferably linear alkyl. R₁ is hydrogen
or methyl and n = an integer from 20 to 150, preferably 5 to 50 and more preferably
5 to 20. Where R is hydrogen the oxyalkyl groups are oxypropyl as a hydrophobe backbone
with oxyethyl or oxyethyl and oxypropyl terminating groups.
[0021] Compounds where R is hydrogen generally have the following formula:
II.

where m may range from 3 to 50 or more and p and q may range similarly as n in Formula
I.
[0022] Illustrative compounds include:
1) n-tridecanol + 7.E.O. (E.O. = ethylene oxide)
2) n-tetradecyl alcohol + 8.E.O.
3) n-hexadecylalcohol + 8.E.O.
4) a C₁₂-C₁₄ linear alcohol containing 55% oxyalkyl of which 42% are ethoxy and 58%
proproxy in a randon distribution.
5) A C₁₈ alkyl linear alcohol containing 57% ethylene oxide.
6)
H(O CH₂CH₂)₅ (OCH₂

) O(CH₂CH₂O)₅ H
[0023] Mixed carbon chain lengths are often, and typically, used since they are very often
quite readily available as mixtures from both synthetic and natural sources.
[0024] The amount of nonionic may range from a few percent up to 35 to 40% on a weight for
weight basis. It is preferred to at least about 3 to 4%. Typical amounts would be
4%, 6%, 8% and in some embodiments 20%, 25% and 30%. Where high non-ionic loading
is desired, then it is preferred to utilize some of the formula in organic polyphosphate
as post added anhydrous (or very low moisture content e.g. 1%, 2% or 3%).
[0025] In general, while other inorganic alkaline materials may be used in preparing the
non-ionic carrier phosphate bead, it is usually less desirable to use silicate at
least as a major replacement for the polymer if not as only a minor replacement for
the polymer materials, and the silicate where employed in this invention for its alkalinity
and anti-corrosive benefits is best utilized as a post added component.
[0026] The silicates which are used in the compositions of the present invention and particularly
those which are post added as powders comprise any of the commercially available alkali
silicates available as powders, wherein the Na₂O to to SiO₂ molar ratio varies from
2:1 to 1:4 and preferably varies from 1:1 to 1:3.5. Typical and most preferred silicates
are sodium and potassium silicates where the Na₂O to SiO₂ molar ratio varies from
1:1 to 1:2.5 and especially the metasilicates (1:1 ratio).
[0027] The physical form of the particulate silicate may be any form i.e. any density, porosity,
shape and particle size. Thus densities may range from a bulk density of 0.3 to one
of 1.5 and preferably 0.4 or 0.5 to 0.7 or 0.8, 0.9 or 1.0.
[0028] Typical particle sizes for the post added silicates may be a product of 20, 30, 40,
50, 60 mesh. A commercially available product with 80-85% or more between 40 & 60
mesh is very useful. Similarly a product with 84% between 10 & 65 mesh is excellent.
[0029] One additional and particularly outstanding characteristic and feature of one aspect
of the the compositions of this invention is their relative low bulk density as compared
to the usual commercial products. Thus for example, while commercial products may
have densities of the order of 0.8 those of the present invention may be made having
20 to 50% less density.
[0030] The silicates used may be in the form of beads, hollow or otherwise, finely divided
powder, regular and irregular and diverse shaped particles. Particularly preferred
silicates are available as Metsobeads from PQ Corporation and Britesil LD24. Mixtures
of any of the foregoing may also, of course, be used.
[0031] The amount of silicate used may vary from a few percent to a significant and almost
major amount such as 2%, 3% and 5% to 10%, 15%, 20%, 30% and 40%. Particularly preferred
ranges are 5% to 25% and 5% to 15%.
[0032] The optional bleach which, however, is highly desirable and preferred can be any
of those conventionally used in autodish compositions. The chloride bleaches described
earlier in the "Background of the Invention and Prior Art" section can also be used
in this invention. Similar amounts may be used as e.g. 0.3% to about 10%, preferably
1% to 5% (by weight). In place of chlorine-yielding (e.g. OC¹⁻) bleaches, one may
use oxygen bleaches such as sodium perborate monohydrate, sodium perborate tetrahydrate,
sodium persulfate, sodium percarbonate and so forth. Oxygen bleach levels may range
from about 2% to 40 or 50% and preferably from about 5% to 30%.
[0033] Many other adjuvants may be added to the present compositions without adversely affecting
their utility and performance. For example, bacteriocides enzymes, anti-spotting agents,
sheeting agents, glaze-damage inhibitors (e.g. boric acid anhydride ) may be used
in amounts from as little as 0.01% to 10%, 15% or more.
[0034] The following examples will serve to illustrate the present invention without being
deemed limitative thereof. Parts, where used, are by weight unless otherwise indicated.
EXAMPLE 1
[0035] An aqueous slurry of anhydrous sodium tripolyphosphate powder, (TPP) water and sodium
polyacrylate powder is prepared at 45% solids level handled and spray dried as in
Example 1 of Joshi U.S. Patent 4414129. Of the spray dried product the TPP comprises
89.55%, the polyacrylate 2.45% and the balance of 8% is moisture in the bead. The
bead has a specific gravity of 0.5 and has considerable mechanical strength.
[0036] The beads so produced are introduced into a rotary drum and post sprayed with a nonionic
surfactant (liquefied) at a temperature of 120°F until 6% by weight of the nonionic
has been "loaded" on the carrier beads. The non-ionic is a C₁₂-C₁₄ linear alcohol
containing about 55% of random oxyethyl and oxypropyl groups (42 wt. % oxyethyl -
58 wt. % oxypropyl groups). These groups are introduced into the alcohol using a mixed
ethylene oxide - propylene oxide stream. The beads at the time of spraying are at
a temperature of about 100° to 105°F. (38 to 41°C). 680g of the "loaded" beads are
then dry mixed with 125g of powdered sodium metasilicate (PQ Corporation Metsobeads),
102 grams of anhydrous sodium carbonate and 33g of sodium dichloroisocyanevate dihydrate.
[0037] In use in an automatic dishwasher 37g of the above formulation are used (in lieu
of 50g of "A" commercial autodish powder). Excellent cleansing is obtained. The spotting
and filming performance is better than "A" commercial, state of the art powder.
EXAMPLE II
[0038] Example I is repeated except that the beads are loaded with 25% by weight of the
non-ionic and the composition is varied somewhat to have the following components:
|
WT. % |
Based Beads of Ex. 1 |
60.0 |
Sodium metasilicate* |
12.0 |
Sodium carbonate of Ex. 1 |
10.0 |
Nonionic of Ex. 1 |
15.0 |
C1. bleach of Ex. 1 |
3.0 |
|
100.0% |
*the metasilicate used here is a high bulk density product (50 lbs/ft³) |
EXAMPLE III
[0039] Example II is repeated except that the amount of base beads is only 50% (and, therefore,
non-ionic is only 12.5%). The additional "hole" of 12.5% in the formula is filled
with sodium tripolyphosphate (anhydrous) which is post mixed and blended into the
formula with the metasilicate, carbonate and bleach.
EXAMPLE IV
[0040] The previous examples are repeated using the non-ionic in each instance, the following:
(a) C₁₈ linear alcohol containing 57% condensed ethylene oxide,
(b) Olin SLF-18-polytergent,
(c) n-tetradecylalcohol + 8 moles of ethylene oxide.
[0041] In preparing the composition of this invention, the usual equipment may be used.
Examples include Patterson Kelly twin shell blender for bath operation and a Patterson
Kelly Ziq-Zag blender for continuous processing.
[0042] Tower conditions and operating parameters for producing the non-ionic carrier-beads
are fully described in the incorporated U.S. Patent 4414129.
1. A free-flowing, automatic dishwashing detergent powder composition comprising water-soluble,
inorganic, polyphosphate base non-ionic surfactant carried by said base and admixed
therewith posdered water-soluble alkalie silicate.
2. A composition as defined in claim1 wherein the polyphosphate base is a spray-dried
bead-like product and comprises from about 50 to 95% by weight, the non-ionic from
about 2% to 40% by weight and the silicate from about 2% to 40% by weight.
3. A composition as defined in claim 2 wherein the polyphosphate is sodium tripolyphosphate,
the non-ionic is a C₁₀-C₁₈ linear alcohol containing at least 5 moles of condensed
ethylene oxide and the silicate is sodium metasilicate.
4. A composition as defined in claim 3 including a water-soluble polymer in the polyphosphate
base.
5. A composition as defined in claim 4 wherein the polymer is a polyacrylate and comprises
0.5% to 10% by weight of the composition.
6. A composition as defined in claim 5 including a bleaching agent.
7. A composition as defined in claim 6 wherein the bleaching agent is a chloroisocyanurate
or an alkali or calcium hypochlorite.
8. A composition as defined in claim 7 including powdered alkaline salts other than
polyphosphate.
9. A method for making a free-flowing automatic dishwashing composition comprising
preparing aqueous slurry of water-soluble inorganic phosphate and a minor amount of
a polymer, spraying drying to form essentially hollow beads, absorbing thereon from
2% to 40% by weight based on the weight of the beads of a non-ionic surfactant having
a melting point below about 150°C by spraying said nonionic in liquefied form onto
said beads and thereafter dry mixing said beads with powdered sodium silicate.
10. A process as defined in claim 9 wherein a powdered chlorine yielding bleaching
agent is dry blended along with the silicate.
11. A method for cleaning dishes and the like in an automatic dishwasher which comprises
adding to the dishwasher, preferably to the dispenser means thereof, the free-flowing
composition of claim 1 and thereafter putting the machine through its normal washing
cycle.