JPH0435520B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention provides an automatic dishwashing detergent composition that has thixotropic properties, improved chemical and physical stability, and can be easily dispersed in a cleaning medium to effectively clean tableware, glassware, ceramics, etc. Regarding. Commercially available household dishwasher detergents that come in powder form have a number of drawbacks. For example, non-uniformity; the production requires costly operations; the tendency to agglomerate at high humidity and form lumps that are difficult to disperse; dusting, which causes particular irritation for allergic users. On top of that,
Liquid forms of these compositions are generally not suitable for use in automatic dishwashers because they are highly foaming, have too low a viscosity, and are too alkaline. Recent research and development efforts have focused on gel or "thixotropic" forms of such compositions, such as disinfectants and dishwashing products characterized as thixotropic pastes. The dishwasher products thus provided are primarily preferred because they are not viscous enough to be "stuck" in the dispensing tip of the dishwasher, and also cause spotty residue on dishes, glassware, china, etc. do not have. Ideally,
Thixotopic cleaning compositions must be highly viscous at rest, Bingham plastic, and have relatively high yield values. However, it must fluidize quickly when subjected to shear stress, for example when squeezed from a shaken orifice in a container, and quickly return to its highly viscous/Bingham plastic state when the shear stress application ceases. Stability is likewise a key consideration, ie there should be no significant phase separation or leakage after long-term storage. It has hitherto been difficult to provide gel-like automatic dishwashing compositions having the above-mentioned properties, especially for compositions used in domestic dishwashing machines. For effective use, automatic dishwasher detergents (hereinafter also referred to as ADD) must contain (1) sodium tripolyphosphate (NaTPP), which softens or traps hard water minerals;
(2) sodium silicate (provides the alkalinity necessary for effective cleaning and protects delicate ceramic glazes and patterns); (3) sodium carbonate (generally an optional ingredient); (4) Cl-releasing agents to facilitate removal of dirt specks leading to water stains; (5) anti-foaming agents/surfactants (to reduce foaming and increase mechanical efficiency); , to provide the necessary cleaning power). For example, SDA Detergents in
Depth, “Formulations Aspects of Maohine
Dishwashing”, Thomas Oberle (1974). Cleaning agents close to the above composition are mostly liquids or powders. It is difficult to combine such ingredients in gel bodies useful for domestic machines. It has been demonstrated that such compositions generally do not contain hypochlorite bleaches but react with other chemically active ingredients, particularly surfactants, to form a suspending or thixotropic agent. For example, US Pat. No. 4,115,308 discloses that suspending agents such as CMC,
A thixotropic paste for automatic dishwashers is disclosed that includes synthetic clays and the like; inorganic salts such as silicates, phosphates, polyphosphates; small amounts of surfactants; and antifoam agents. Bleach is not disclosed. The same applies to U.S. Patent No. 4147650,
Additionally, hypochlorite bleaching agents are disclosed. However, the product is described as a detergent slurry. U.S. Patent No. 3,985,668 discloses (1) a suspending agent,
Colloid-forming clays, preferably of the smectite, attapulgite type; (2) abrasives, such as silica sand or perlite; (3) in addition to being buoyant and thus serving as a filler, Abrasive filters of gel-type consistency containing fillers consisting of low-density powdered polymers, expanded perlite, etc. that have a stabilizing effect and displace the water available for undesirable supernatant layer formation due to leakage and phase de-stabilization. Stain cleaning agents are listed. The above are essential ingredients.
Optional ingredients are hypochlorite bleaches, bleach-stable surfactants, buffers such as silicates, carbonates, monophosphates, and the like.
Builders such as NaTPP can be included as another optional ingredient to provide or supplement bulking functions not provided by buffers. According to the patented invention, the amount of such builders does not exceed 5% of the total composition. Maintenance of the desired PH>10 is made possible by buffers/builders. high
It is stated that PH minimizes the degradation of Cl-based bleaches and undesirable interactions between surfactants and bleaches. When present, NaTTP is 5 as described above.
%. Antifoam agents are not disclosed. The present invention provides a thixotropic, gel-type structure which is particularly suitable for automatic dishwashing machines, especially those of the type found in the home, and which has the desirable properties necessary for effective cleaning in such automatic dishwashing machines. Improved detergent compositions have been discovered that include each of the various ingredients. Accordingly, one main object of the present invention is to provide a detergent composition having thixotropic properties and particularly suitable for use in automatic dishwashing machines. A second objective is to provide a composition with good physical stability in which no significant phase separation is evident even after long periods of standing. A third object is to provide compositions in which problems associated with undesirable interactions between chemically active ingredients are free or at least substantially reduced. Another object is to provide compositions having said stability in highly alkaline conditions necessary for effective detergent properties. Yet another object is to provide a composition having improved flow properties which exhibits high viscosity at low shear rates and low viscosity at high shear rates and is therefore advantageously suitable for use in the dispensing cup of an automatic dishwasher. This is the offer. Yet another object is to provide a composition that has low foaming properties, improved cleaning performance, and is easily dispersible in a washing machine. Other objects and advantages of the invention will be apparent from the description herein. The above objects are achieved by the present invention which provides a composition which is usually in the form of a gel. That is, the present invention provides an aqueous composition for an automatic dishwasher comprising: (a) a water-soluble alkali metal tripolyphosphate having an average degree of hydration of from 5 to 35% and from 1 to 5; (b) from 2.5 to 20%. of sodium silicate, (c) 4-9% of a water-soluble alkali metal carbonate, (d) 0.1-5% of a bleach-stable water-dispersible organic surfactant, (e) 0.1-0.5% of phosphoric acid. , mono- and/or di-( _C16 - _C18 ) alkyl esters; (f) 3-20% NaOCl solution containing 13% available Cl; (g) 1.5-10% NaOCl solution; , colloid-forming clay-based inorganic thickener, and (h) the pH of the composition when measured as a 1% aqueous solution.
of sufficient amount to give a PH of 10.5 to 13.5.
NaOH, the amount of phosphate ester is sufficient to provide low foaming properties, the amount of NaOH is at least sufficient to neutralize said phosphate ester, and the amount of NaOH is at least sufficient to neutralize said phosphate ester, and the amount of NaOH is at least sufficient to provide a thixotropy of 2.5 to 10. having an index,
The present invention provides an aqueous composition for automatic dishwashers. The ADD composition thus formulated is low foaming; chemically and physically stable; easily soluble in cleaning media; best PH value for improved cleaning, i.e. PH 10.5
~13.5, is most effective. The compositions usually have a gel consistency, ie, are highly viscous, opaque, jelly-like materials with Bingham plasticity and therefore relatively high yield values. Therefore, a certain shear force is required to initiate or increase flow within an agitated dispensing cup for an activated automatic dishwasher. Under such conditions the composition fluidizes quickly and is easily dispersed. Upon cessation of the shear force, the fluid composition returns to its highly viscous Bingham plastic state, closely approaching its previous consistency. In general, ADD effectiveness is directly related to (a) available Cl content; (b) alkalinity; (c) solubility in the cleaning medium; (d) antifoam efficiency; and importantly, ADD composition. PH of about 10.5 to 13.5, preferably at least about 11.5
It is to do so. Therefore, the use of NaOH is essential in the present invention. ADD without using NaOH
This is because the pH is less than 10.5. At this PH, the ADD is too viscous, ie, solid, and does not readily flow under the shear forces in the dispensing cup under normal machine operating conditions. The composition essentially loses much, if not all, of its thixotropic properties. Therefore, in that case, it is essential to add NcOH to increase the pH and fluidity. The presence of carbonate is often necessary in the present invention. This is because it acts as a buffer that makes it possible to maintain the required pH. However, excess carbonate should be avoided as it may cause the formation of carbonate needles and impair the stability and/or functionality of the ADD product. Caustic soda serves another important function: neutralizing phosphate ester antifoam agents. Other criteria governing the selection of ingredients in this invention and essential to providing a stable and effective ADD product with thixotropic properties are as follows. NaTTP must be free of heavy metals. This is because heavy metals tend to decompose sodium hypochlorite. On average, NaTPP contains about 5-15 w% water, which corresponds to an average degree of hydration of about 1-5. If only the hexahydrate is used, the detergent product will be a liquid and will have very little, if any, thixotropy. Anhydrous NaTPP
If you use vinegar, the product will be too thick and unsuitable. The effective composition uses, for example, anhydrous and hexahydrate NaTPP in a weight ratio of 0.5:1 to 2:1. The ratio is approximately 1:
1 is particularly preferred. Antifoam agents can increase dishwasher efficiency and reduce destabilizing effects that can occur due to the presence of excess foam within the washer during use. In the present invention, the effective Cl amount is provided by, for example, sodium hypochlorite rather than dichloroisocyanurate, which is used in current powder detergents. The ADD product exhibits improved flow properties as assessed by testing product viscosity as a function of shear rate. Studies have shown that the composition exhibits high viscosity at low shear rates and low viscosity at high shear rates, with data indicating efficient fluidization and gelling within the shear rates present in dishwashers. was confirmed. From a practical standpoint, this means improved pourability, processability, and less leakage in the dispensing cup compared to traditional liquid ADD products. 3～
Applying a shear rate corresponding to 30 rpm, the viscosity (Bruckfield) is correspondingly 15,000-30,000 cps to approximately 3,000 when measured at room temperature on an LVT Bruckfield viscometer after 3 minutes using a #4 spindle.
~5000cps. Shear rate 7.4s ^-1 spindle
Corresponds to approximately 3 rpm. An approximately 10-fold increase in shear rate decreases the viscosity by a factor of 3-7. For conventional ADD gels, the corresponding decrease in viscosity is only about 2 times. Moreover, such compositions have an initial viscosity of only about 2500-2700 cps at about 3 rpm. Accordingly, the compositions of the present invention exhibit critical fluidity circles at low shear rates, which are significantly greater in terms of shear rate increase versus viscosity decrease.
This property of the ADD product is summarized as the thixotropic index (TI), which is the ratio of (a) the apparent density at 3 rpm and (b) the apparent density at 30 rpm. The composition has a TI of about 2.5-10, preferably 6-8.
Each of the ADD compositions tested returned substantially and quickly to its previous resting state consistency upon cessation of shear. In the production of ADD products, inorganic salts, such as carbonates, silicates, and tripolyphosphates, are first dissolved or dispersed in any aqueous medium. Add the thickening agent last. Like the thickening agent, the phosphate ester antifoaming agent is mainly provided as an aqueous dispersion. The ester dispersion, caustic soda, and inorganic salt are first mixed in a water (deionized water) solution at high temperature and then cooled (while stirring). The room temperature bleach, surfactant, thickener dispersion is then added to the cooled (25-30°C) solution. The amount of water used should be approximately 35 to 75%, preferably approximately 50 to 65%, of the active ingredient concentration (hereinafter referred to as AI concentration) of the ADD product.
shall be. In the present invention, the inorganic salt accounts for about (a) 5 to 35%, preferably about 20 to 30% of the total weight of the product.
NaTPP; (b) 2.5-20%, preferably about 10-15%;
Sodium silicate with a Na ₂ O:SiO ₂ ratio of approximately 0.3 to 0.5%: (c) 4 to 9%, preferably 4 to 7%, of an alkali metal carbonate, preferably sodium carbonate. These salts should provide a total salt concentration of about 20-50%, preferably about 35-45%. The bleach consists of an approximately 3-20%, preferably 7-12%, sodium hypochlorite (NaOCl) solution containing 13% available Cl. The caustic soda, as described above, is in an amount sufficient to maintain a pH of from 10.5 to about 13.5, preferably from about 11.5 to about 12.7. Generally, the amount will be about 0.5 to 3%, in each case at least sufficient to neutralize the antifoaming phosphate ester compound. Preferred antifoam agents consist of about 0.1-0.5%, preferably about 0.15-0.3% mono- and/or di- _C16-18 phosphoric acid alkyl esters. The specific amount depends in part on the amount of surfactant present. Surfactants useful in the present invention must be stable in the presence of hypochlorite bleaches and are preferably of the anionic, amine oxide, phosphine oxide, sulfoxide, betaine type, with the former being most preferred. They are about 0.1 to 5
%, preferably about 0.3-0.8%.
It is generally desirable to maintain a surfactant:antifoam weight ratio of about 10.1 to 1:1, preferably about 1.5:1 to 4:1 to ensure sufficient antifoam.
Particularly preferred surfactants according to the invention are linear or branched alkali metal mono- and/or di-C _8-14 alkyl diphenyl oxide mono- and/or disulfonates, such as DOWFAX 3B-2,
Commercially available as DOWFAX 2A-1,
It is. It has been found that, in general, paraffin sulfonates tend to impair, if not destroy, thixotropy and increase viscosity too much, causing serious shear problems. Additionally, the surfactant must be compatible with the other components of the composition. Other suitable surfactants are p-alkyl sulfates, alkyl sulfonates, alkylaryl sulfonates, s-alkyl sulfates. Examples are sodium C _10-18 alkyl sulfates such as sodium dodecyl sulfate; sodium tallow alcohol sulfate; sodium C _10-18 alkanesulfonates such as sodium hexadecyl-1-sulfonate;
Sodium such as dodecylbenzenesulfonate
_C12-18 alkylbenzene sulfonates; and their corresponding potassium salts. Other suitable surfactants, amine oxide surfactants as detergents, typically have the structural formula:
R ₂ R ¹ NO (each R is lower alkyl, e.g. methyl, R ¹ is C _8-22 long chain alkyl, e.g. uralyl, myristyryl, palmityl, cetyl)
It is indicated by. The corresponding surfactants phosphine oxide R ₂ R ¹ PO or sulfoxide RR ¹ SO can be used instead of the amine oxide. Betaine surfactants typically have the structural formula:
R ₂ R ¹ N+R″COO− (each R is lower alkyl,
R ¹ is long chain alkyl as described above and R″ is C _1-5
alkylene). Specific examples of these surfactants are lauryl-dimethylamine oxide, myristidimethylamine oxide, cocodimethylamine oxide, hardened tallow dimethylamine oxide, the corresponding phosphine oxides, sulfoxides, and dodecyldimethylammonium acetate, tetradecyl-diethylammonium Corresponding betaines include pentanoate and hexadecyldimethylammonium hexanoate. From the viewpoint of biodegradability, the alkyl in these surfactants should be linear, and
preferable. All of the above types of surfactants are well known in the art, for example US Pat. No. 3,985,668;
It is described in Publication No. 4271030. Thickening or suspending agents useful in this invention generally include:
It consists of inorganic colloid-forming clays of the smectite and/or attapulgite type, the former being preferred. These substances affect the fluidity of the composition;
It is used in an amount of about 2.5-4%, the amount selected in each case being sufficient to provide the desired Bingham plasticity. Smectite clays include montmorillonite (bentonite) (preferred), hectorite, saponite, and the like. This type of material is available from the American company Georgia Kaolin as Thixogel.
It is available under trade names such as No. 1 and Gelwhite GP (both montmorillonite). Attapulgiaite clay is manufactured by Engeltard Minerals and
From the Chemicals company, the trade name is Attagel, i.e.
These are commercially available substances such as Attagel 40, Attagel 50, and Attagel 150. Mixtures of smectite and attapulgite in a weight ratio of 4:1 to 1:5 are useful in the present invention. Suspending agents of the above type are well known to those skilled in the art and are described, for example, in the aforementioned US Pat. No. 3,985,668. Other ingredients useful in the present ADD compositions include dyes to provide a pleasantly colored composition. Particularly preferred are polysulfides of chlorinated phthalocyanine and aluminosilicate, which give green and blue colors, respectively. The following examples are for illustrative purposes only and are not to be construed as limitations on the invention. In this specification, percentages are based on the total composition unless otherwise specified. EXAMPLE A predispersion of an antifoam agent in water (6 g) consisting of a 2:1 mixture of a phosphoric acid mono(C _16-18 ) alkyl ester and the corresponding diester is mixed for 30 minutes at 60° C. using a disk impeller. It was prepared by
This dispersion is called a dispersion. GELWHITE GP (hydrate) thickener (3g)
A predispersion in water (17 g) was prepared by mixing for 10 minutes at 70° C. using a Z-blade mixer. This dispersion is called a dispersion. The following ingredients were mixed in a Giusti mixer at 50-60°C.

[Table] Opaque composition with gel-like consistency (approximately 40% AI)
I got it. According to the above-mentioned method, the present composition has about 7
I found out I have TI. This is each
Apparent viscosity value 28000cps at 3rpm and 30rpm,
Based on 4000cps. When tested in an automatic dishwasher equipped with a dispensing cup, the composition exhibited excellent cleaning power and dispensed easily and quickly. The composition was observed to be preferably non-foaming. Little or no phase separation was observed even after long-term standing in a closed container. The pH of this composition is 1%
When measured as an aqueous solution, it was 11.6. Upon performing a shear test evaluation, the composition was observed to quickly return to its previous resting consistency, within said limits, i.e. within shear force limits at least close to the values present in an operating automatic dishwasher. The tests did not show any appreciable loss in yield value. There was no discernible difference when the ADD product was dispensed with a squeeze tube rather than a dispensing cup. Example 1 illustrates repeating the combined polyphosphate carbonate-silicate concentration of about 37%, while the total concentration of such salts is varied within the aforementioned limits. Combined use - when the salt concentration is at least about 30%,
In particular, best results are obtained when the sodium tripolyphosphate concentration is at least about 20%. A high silicate concentration is desirable for protecting ceramic graves and patterns, and also provides high alkalinity.
This can be offset by appropriately reducing the caustic soda concentration and/or adjusting the sodium carbonate (buffer) concentration. The present compositions appear to be most sensitive to changes in NaTPP concentration (higher concentration ranges are more effective and their degree of hydration; variations in surfactant concentration generally result in lower antifoam concentration). A corresponding direct variation will be necessary to achieve the desired low foaming. A reduction to a composition PH below about 10.5 is accompanied by a significant decrease in composition effectiveness and a corresponding decrease in flowability. Similar results were obtained by substituting the corresponding ingredients in the method of Example 1 with an alkyl sulfate surfactant, such as sodium coconut alkyl sulfate, an attapulgite clay, such as Attagel 50; a 2:1 mixture of montmorillonite and Attagel 50. Small amounts, e.g. 0.003-0.05%, of chlorinated phthalocyanine and aluminosilicate dyes, respectively, were added to the composition of Example 1 (included with the pre-thickener dispersion or post-added to the cooling solution). A green composition and a blue composition with excellent colors were respectively obtained.While the present invention has been disclosed with reference to preferred embodiments thereof, changes and modifications thereof which will be apparent to those skilled in the art are contemplated by the present invention. It is clear that it is included within the spirit and scope of.

Claims (1)

[Scope of Claims] 1. An aqueous composition for an automatic dishwasher comprising: (a) a water-soluble alkali metal tripolyphosphate of 5 to 35% and having an average degree of hydration of 1 to 5; (b) 2.5 to 20%; % sodium silicate, (c) 4-9% water-soluble alkali metal carbonate, (d) 0.1-5% bleach-stable water-dispersible organic surfactant, (e) 0.1-0.5% phosphoric acid. (f) _3-20 % NaOCl solution containing 13% available Cl; ₍ g) 1.5-10% When the pH of the colloid-forming clay-based inorganic thickener and (h) composition is measured as a 1% aqueous solution,
of sufficient amount to give a PH of 10.5 to 13.5.
NaOH, the amount of phosphate ester is sufficient to provide low foaming properties, the amount of NaOH is at least sufficient to neutralize said phosphate ester, and the amount of NaOH is at least sufficient to neutralize said phosphate ester, and the amount of NaOH is at least sufficient to provide a thixotropy of 2.5 to 10. having an index,
Aqueous composition for automatic dishwashers. 2 The weight ratio of surfactant and antifoaming agent is 10:1 or more
A composition according to claim 1, wherein the ratio is 1:1. 3. The composition of claim 1, wherein the total concentration of tripolyphosphate, silicate, carbonate is at least 20%. 4. The composition according to claim 3, wherein the tripolyphosphate concentration is 20 to 30%. 5. The composition of claim 1, wherein the tripolyphosphate comprises a mixture of its substantially anhydrous and hexahydrate forms in a corresponding weight ratio of 1:2 to 2:1. 6. The composition of claim 5, wherein the weight ratio is 1:1. 7. The composition of claim 1 further comprising a pigmented amount of dye. 8. The composition according to claim 1, wherein the thickening agent is smectite and/or attapulgite clay. 9. The composition of claim 1, wherein the surfactant is an alkali metal _C8-14 alkyl diphenyl oxide sulfonate. 10 The tripolyphosphate is sodium tripolyphosphate, the carbonate is sodium carbonate, and the surfactant is mono( _C8 - _C14 alkyl) diphenyl oxide disulfonate and di( _C8 - _C14 alkyl) 2. The composition of claim 1, wherein the composition is a mixture of diphenyl oxide disulfonates and the thickening agent is bentonite. 11. The composition of claim 10, wherein the composition has a PH of 11.5 to 12.7. 12. The composition of claim 10, wherein the composition has a thixotropic index of 6-8.