JPH0757879B2 - Dishwasher detergent composition - Google Patents

Description

The present invention relates to a liquid dishwasher detergent composition suitable for use in cleaning food stains from cooking utensils, dishes and glasses. In particular, the invention relates to an aqueous thixotropic structural system containing an alkalinity source and a builder salt.

The use of liquid form detergents in dishwashers has several advantages over powdered or granular detergents. Such advantages include easier handling during dispensing and administration, lump formation, no "caking" and dust, and good solubility.

However, liquid detergents must meet certain requirements. First, liquid detergents must be a uniform mixture of ingredients in order to deliver the optimal combination of active ingredients with each dose wash. In most current formulations, it is necessary to shake the liquid before each use to remix the ingredients. The preferred product is the physical separation and segregation (segr) of the active ingredient.
should be stable against egation). The high viscosity at low shear rates helps the physical stability of the liquid and protects it from the separation of active ingredients.

Physical stability can be obtained by using suspension or thickening systems to enhance the rheological properties of liquids. These agents are required to maintain viscosity at low shear rates at the high ionic strength conditions present in well-formed liquid detergents, to aid other components of the composition, especially soil removal. It must be chemically compatible with the chlorine bleach used.

Liquid dishwashing detergents must be compatible with currently available dishwashing equipment. Household dishwashers use detergent cups designed to contain powdered or granular solid detergent and dispense it into a particular wash cycle, but this cup is not designed to contain low viscosity liquids. It has not been. Therefore, the liquid used as a dishwasher detergent should have a high viscosity so that it is effectively retained in the cup and does not leak into the dishwasher during the cycle prior to washing. Excessive leakage can lead to dose deficiencies in the wash cycle and affect wash performance.

Although high viscosity is desirable during storage or when the material is in the detergent cup, the liquid must be easily and conveniently dispensed from the container. That is, for this application, a liquid is preferred in which the viscosity decreases when a shearing force is applied and the decrease is reversible after the shearing force is removed. This behavior is called "shear-thinning",
Recommended for liquid dishwashing detergents. When the liquid contained in the container is squeezed or shaken to be stirred, sufficient shear stress is applied to cause shear softening behavior and the fluidity of the liquid increases. Optimal flow characteristics allow for a liquid that remains viscous enough to prevent or minimize excessive leakage at higher shear rates but is easily pourable. The liquid should promptly reacquire its structure after dispensing. The characteristic of this liquid is called "thixotropy".

Disclosed are thixotropic liquid detergent compositions suitable for use in dishwashing detergents that are structured by the interactions between the components that positively affect the rheology of the components and that do not require the inclusion of conventional thickeners. The effects are seen in increasing viscosity and increasing yield point.

A number of systems for thickening dishwashing detergent compositions have been disclosed in the prior art. British Patent No. 1 527 706
The publication discloses a slurry that is structured by adding a synthetic polymer. However, it is conceivable that liquids containing, for example, polyacrylate as the only structured material will have poor cup retention due to the low yield point. British Patent No. 2 140 450 discloses liquids structured with clay. Clays reduce the amount of active ingredient that can be dispensed in each dose and, in addition, the presence of insoluble clay minerals in the amounts used for structuring can adversely affect the speckle and cloudiness of glass. Also, the use of biopolymers or cellulosics in a liquid detergent base to provide a thickening system,
For example, U.S. Pat.No. 4,226,736 and U.S. Pat.
Proposed in the issue. It can be seen that these systems are unstable as most biopolymers react readily with hypochlorite, with a gradual loss of viscosity in the presence of hypochlorite.

In other fields, such as thickening bleach systems, micellar structured liquids are known which usually contain 90% by weight or more of a hypochlorite solution and are free of builders (UK patent 1 466 560.
issue). Systems which are thickened by a synergistic effect with urea are also known (eg British Patent 1 579 668). British Patent No. 2 1
85 037 describes aqueous thixotropic dishwashing detergents which are structured with aliphatic mono- or polycarboxylic acids.

The present invention relates to a thixotropic liquid detergent composition containing an alkali metal builder, an alkali metal silicate, a stabilizer containing 0.05 to 5% by weight of an alkyl phosphate, phosphonate, sulfate or sulfonate, and optionally a detergent active ingredient. I will provide a.

The invention is based on the finding that the alkyl derivatives can be used as liquid stabilizers. Although the use of alkyl phosphates as defoamers in dishwasher detergent compositions has been previously described, the inventors believe that their use as liquid stabilizers has not previously been described. . Structuring occurs independently of the presence of active detergent.

Further, it is preferable to incorporate a bleaching agent such as hypochlorite into the composition of the present invention. In contrast to some conventional systems where the presence of hypochlorite is said to destroy the stability of the system, this system is also stable when it contains these bleaching agents.

The composition of the present invention has excellent rheology and stability,
The active ingredients can be distributed very evenly in the dishwasher wash cycle. The structuring is also improved so that it can be easily dispensed from the product container to the dispenser and from the dispenser to the dishwasher wash cycle in a reasonable amount of time.

The system of the present invention has excellent stability to physical separation on storage and provides a more uniform product. When the physical stability is poor, the liquid layer and the solid layer are separated to form a layered liquid. When this occurs, the user must shake the container vigorously and remix.

In addition, the structured system of the present invention can be tailored for optimal liquid rheology at low shear rates, physical stability, cup retention, and moderate shear rate flow during dispensing into the wash cycle. Give behavior.

The product of the present invention is a thixotropic dishwashing detergent composition in the form of a slurry. This product has a yield point of 5 to 50 Pa and a viscosity of 500 to 5000 mP at 20 ^-1 s.
with as (Haake RV2, MV2 rotor at 20 ° C.).

Stabilizers of the present invention are long chain alkyl, ie C ₁₀ -C ₂₂ alkyl sulfates, sulfonates, phosphates, phosphites or phosphonates. Preferred are phosphorus-containing compounds, and particularly preferred are compounds selected from the compounds listed in Table 1 below or mixtures thereof.

Wherein R and R ¹ are the same or different C ₁₀ -C ₂₂ alkyl chains. Most preferred is a mixture of C ₁₆ / C ₁₈ alkyl dihydrogen phosphate and dialkyl hydrogen phosphate, hereinafter referred to as ALF. -5 (Lancro Chemicals Limite
Notated as d).

Higher alkyl phosphates and phosphonic acids are also preferred because they tend to reduce metal corrosion and erosion of the enamel surface.

If sulphates or sulphonates are used, for example alkylbenzene sulphonates, it is preferred to additionally use phosphates or phosphonates.

The alkali metal condensed phosphate can be present in the composition as a sequestrant or builder for water hardness. Tripolyphosphate is the preferred sequestrant, although pyrophosphate, hexametaphosphate or other condensed phosphates may be used. The sequestering agent is present in the composition at 0.1-35.
It should be present in an amount by weight, preferably 15-30% by weight. The use of sequestering agents such as sodium tripolyphosphate in the composition above the solubility limit results in the solids being present as fine particles suspended in the structured system. The presence of solids affects the viscosity of liquids and is the structuring component needed to distribute the proper rheology.
The amount of urants) may change. It is also possible to use zeolite as a builder.

The alkali sources are used in combination in a more preferred embodiment of the invention. Alkali metal carbonate may be used as an alkaline buffer and may be present in an amount of 0 to 30% by weight, more preferably 2 to 10% by weight.

A pure alkali metal metasilicate or an alkali metal silicate (or a mixture of two or more metasilicates and / or silicates) having a molar ratio SiO ₂ / (Na ₂ O and / or K ₂ O) of 1.0 to 3.25 is used as an alkali source and , Can be used as an anti-corrosion agent to protect metal and earthenware surfaces from harsh alkaline environment during cleaning. The silicate is used in the form of an aqueous solution or a solid and is
-30% by weight, more preferably 2-20% by weight.

Alkali metal hydroxides can be used as a source of alkalinity and as a means to raise the pH of the liquid detergent concentrate to stabilize the hypochlorite. Sodium or potassium hydroxide in the form of an aqueous solution or as a solid can be used in the composition in an amount of 0.1 to 25% by weight, preferably 0.5 to 15% by weight.

Polymers can be added to the system to provide a more builder effect. The polymers used are synthetic and water-soluble. Examples of applicable polymers are polyacrylic acid and its alkali metal salts, polymethacrylic acid and its alkali metal salts, and their copolymers with alkyl acrylates and alkyl methacrylates, these with maleic anhydride, polyacrylamide and partially hydrolyzed. Copolymer with decomposed polyacrylamide, polyacrylonitrile and its partially hydrolyzed product, polymethacrylonitrile and its partially hydrolyzed product, polystyrene sulfonic acid and its alkali metal salts, polymaleic anhydride and its product Polymers of alkali metal salts, poly n-vinyl lactams (poly-vinyl pyrrolidone, poly (N-vinyl caprolactam), etc.), and N-substituted acrylamides, or mixtures thereof. These polymers have a weight average molecular weight of 1,000 to 15,000,000, preferably 1
It has 0,000 to 400,000, most preferably 100,000 to 250,000 and can be used in acid or neutralized form. The polymer should be a hypochlorite stable type, with polyacrylates and polymethacrylates being most preferred. The polymer should be pure so that there is a minimal amount of unsaturated monomers, chemically reactive initiators and terminators or surfactants that accelerate the rate of decomposition of hypochlorous acid.
The polymer is present in the composition in an amount of 0.05 to 10% by weight, preferably 0.1.
~ 0.5 wt% can be present.

Clays such as hectorite and montmorillonite may be included in the compositions of this invention. These help reduce speckle formation in glassware and range from 0.5 to 20
It can be present in an amount of% by weight. The presence of the structuring agent that characterizes the present invention aids in the production of the low viscosity, stable clay structure products described in the art without the need for the placement of known structuring agents such as polymers, active ingredients, etc. I understood. Especially preferred is laponite cla
y) 0.5 to 2% by weight is added. As the solids concentration increases, less stabilizer may be needed to obtain stability.

The system can incorporate a bleaching agent-forming system such as hypochlorite in an amount of 0.5 to 5 weight percent active chlorine. The active ingredient can optionally be included in the system. Preferred are nonionic active ingredients, but may also contain minor amounts of anionic actives such as secondary alkyl sulphates.

Conventional additives such as colorants and fragrances can be present in the composition in amounts not exceeding 5% by weight. Other antifoaming agents can also be included.

The product of the present invention can be prepared by first preparing a premix consisting of a stable component and water, adding the premix to a mixture of silicate and alkali metal hydroxide, and further adding a builder and hypochlorite. . This method is 40 ℃
It is preferable to carry out the above.

The products of the invention are found to have a high degree of stability at room temperature and yet exhibit a stable low viscosity which aids in partitioning. The pH of the composition can be 10-14, preferably 12-13.5. The products of the present invention exhibit superior cleaning performance as compared to other thickened dishwashing detergent systems.

The invention is further described below by means of non-limiting examples.

Examples Example 1 A basic dishwasher detergent liquid system was prepared by adding various amounts of ALF-5 and investigated for viscosity and stability.

Example 2 In order to investigate how the stability was improved, various amounts of
ALF-5 was incorporated into the viscosity structure system.

Example 3 The following composition was prepared and was found to be stable at room temperature and 37 ° C for 8 weeks.

Claims (6)

[Claims] 1. An alkali metal builder of 0.1 to 35% by weight, an alkali metal silicate of 0.1 to 30% by weight, and 0.05.
An aqueous thixotropic liquid detergent composition comprising -2% by weight of a long chain alkyl phosphate, a stabilizer selected from a long chain alkyl phosphite and a long chain alkyl phosphonic acid, the composition being substantially clay. And long-chain fatty acids as thixotropic thickeners, the stabilizer being present in an amount sufficient to give the composition a yield point of 5-50 Pa and a viscosity at 20 s ^-1 of 500-5000 mPas. . 2. A composition according to claim 1, which additionally contains 0 to 5% by weight of chlorine bleach-stable organic detergent actives. 3. A composition according to claim 1, which additionally contains a bleaching agent which gives 0.5 to 5% by weight of available chlorine. 4. Substantially (a) 0.1 to 35% by weight of alkali metal phosphate, (b) 0.1 to 30% by weight of alkali metal silicate, (c) 0 to 15% by weight of NaOH, and (d) 0 to 0% of alkali metal carbonate. 30% by weight, (e) 0.05 to 2% by weight of long-chain alkyl phosphate, long-chain alkyl phosphite and long-chain alkylphosphonic acid (f) Chlorine bleach in an amount corresponding to 0.50 to 5% by weight of available chlorine, and ( A composition according to claim 2 in which g) the rest comprises up to 100% by weight of water. 5. A method of making an aqueous liquid thixotropic detergent composition according to claim 1, comprising: (a) forming a mixture of water and at least some builders or silikes; A stabilizer consisting of a long-chain alkyl phosphate, a long-chain alkyl phosphite and a long-chain alkyl phosphonic acid to the mixture, and (c) the remaining builder or silicate, and the remaining components of the composition to the mixture. Including the method. 6. A method according to claim 5, comprising adding up to 5% by weight of the final composition of a second alkyl sulphate to the mixture.