JPH07799B2 - Detergent composition - Google Patents

Description

The present invention relates to detergent compositions, in particular liquid dishwasher detergent compositions suitable for cleaning food stains on utensils, dishes, cups and similar appliances.

More particularly, the present invention is a stable, pourable aqueous system consisting at least in part of an insoluble builder salt and a soluble alkali silicate, essentially containing conventional structurants. Not related to composition. This system is characterized by its thixotropic properties.

Detergents for use in domestic dishwashers are generally available in powder or granular form. However, such solid compositions present many disadvantages to manufacturers and users. Compositions commonly used in powder detergents must be constructed with additional manufacturing equipment because the compositions generally cannot be spray dried during manufacture. The powder is
Often contains large clumps created by caking when stored in high humidity. This makes dispersibility difficult. The powder form of the product is often very dusty, which can affect dispensing as well as cause irritation.

The use of machine dishwashing detergents in liquid form eliminates many of the above disadvantages, which are solely due to the fact that they are powders. However, liquid detergents must meet several requirements. First of all, the liquid must be a homogenous mixture of ingredients in order to deliver the optimum combination of active ingredients to the wash at each dose. By active ingredient is meant the ingredient that is actually involved in the cleaning, rather than acting as a filler. Many prior art formulations require the liquid to be shaken before each use in order to remix the various components.

Preferred products should be stable to the physical separation and segregation of the active ingredients during storage. Granular solids, such as detergent builders, should remain suspended in the liquid detergent. Some kind of structuring system is required to keep the solids in suspension. In aqueous detergent liquids, "external structurin"
g), ie by adding an additional component such as a polymer or clay or by using the interaction of water in the liquid with the active ingredient of the detergent itself to form an “internal structure” to support the solid ( This can be achieved, for example secondary alkane sulfonates and phosphonates). In all cases, microscopic studies have shown that some type of suspension network is formed.

The term "structuring agent" as used herein should therefore be understood to mean any constituent, such as clays, polymers or biocellulosic materials. It is present in a suitable amount inside the liquid and structures it, usually by the formation of a network. The use of small amounts of such structuring agents, especially clay, should not be considered excluded from the composition. Even such small amounts can act as a builder or rinse aid. The critical amounts of the components in question will be determined solely by reference to experience or prior art.

For dishwasher use, the detergent must be compatible with currently available dishwashing equipment. Household dishwashers use detergent cups designed to contain powdered or granular solid detergent and to deliver it to a particular wash cycle. The cup is usually placed vertically on the dishwasher door and is not designed to contain low viscosity liquids. Therefore, the liquid used as a machine dishwashing detergent must have sufficient viscosity to be effectively retained in the cup and to prevent leakage to the machine during the cycle prior to cleaning. . Too many leaks can result in too little dose in the wash cycle, which can affect wash performance. However, they must not be so viscous that they cannot be washed out of the dispensing cup in a reasonable time.

Several prior arts disclose methods of thickening liquid dishwashing compositions by mechanism and methods of imparting some stability. British Patent 1,527,706 discloses slurries structured with the addition of synthetic polymers. However, for example, a liquid containing polyacrylate as the only structuring agent has a low yield point and is considered to have poor cup retention. British Patent No. 2,140,450 discloses clay structured liquids. The addition of this clay reduces the amount of active ingredient that can be produced in each dose. In addition, the presence of insoluble clay minerals can adversely affect glass spotting and film forming performance. The use of biopolymers or cellulosic materials in liquid detergent bases for thickening is also described, for example in British Patent 4,
226,756 and U.S. Pat. No. 4,260,528. Most biopolymers react readily with substituting chlorates, making these systems unstable, with a gradual decrease in viscosity in the presence of substituting chlorates. British Patent No. 2,
185,037 discloses the use of long chain fatty acids to provide a thickening effect.

All of the systems described in the prior art are structured in principle by the use of external network-forming structuring agents, these liquids generally having shear thinning properties. That is, they exhibit high viscosity at low shear rates and low viscosity at high shear rates. Furthermore, this represents the thixotropic property of liquids, and the viscosity of these liquids and the time after the occurrence of distortion are time-dependent.

The present invention utilizes various principles to obtain a stable liquid system that can be poured. In contrast to the prior art, the present invention does not use a network-forming structuring agent. Because such structuring agent is believed to be important to hold to remain fully suspended current solid particles under technical conditions are not present, the present invention is the shear rate value 1～100Sec ^{- It} includes liquid systems (dispersions) that are Newtonian (eg, not shear thinning) over a wide range of ¹ . At extremely low shear rates that require special equipment for measurement (accommodating stress Deer rheometer), Newtonian behavior (Newt
The deviation from the onian behavior) becomes more prominent. This is a theory developed to explain the rheological behavior of concentrated dispersions (“Inleiding in de Reologie, Reometrie, D
isperstereologie en Polymeerreoiogie ", Blom C, Jongs
chaap RJJ, Mellema J, Technische Hogeschool Twente K
luwer Technesche Boeken, 1 Druk 1986). Therefore, according to the current state of the art, these dispersions cannot be expected to be physically stable. A rapid settling will occur.

Without being bound to any theory, it is believed that the compositions of the present invention exist as solid individual particles and not as agglomerates. By choosing a water-soluble alkali metal silicate with an appropriate SiO ₂ / M ₂ O (M = K, Na) ratio, it is possible to obtain a deaggregated system exhibited by this phenomenon, the pseudo-Newtonian behavior. Addition of electrolytes can extend the range in which the desired rheological behavior is observed. The deagglomeration effect can be shown by the following observation results. That is, 20%
Addition of 40% Zeolite 4A to a sodium disilicate (ratio 3.6) solution produces a viscous, shear thinning and unusable paste that is outside the scope of this invention. When the silicate ratio is adjusted with NaOH or KOH, the viscosity is significantly reduced and a thin, pourable, pseudo-Newtonian system is obtained by deagglomeration of the particles.

According to the invention, a stable viscous composition comprising: (a) a detergent builder present in at least partially insoluble form; (b) a soluble alkali metal silicate having a ratio of 0.5 to 3.0 (silica to alkali); and (c) water. A thick liquid detergent composition is provided, wherein the composition has a thixotropic index of 2.5 to 0.5, and the composition is essentially free of structuring agent. To be done.

The ratio of alkali metal silicate is 0.5 to 3.0, preferably 0.5.
~ 2.2, more preferably 0.6-1.9.

The preferred rheological behavior is indicated by the thixotropic index (TI), which should be between 0.5 and 2.5. The thixotropy index is referred to herein as (a) 3 rpm and (b).
It is defined as the ratio of the apparent LVT Brookfield viscosity of the sample after 3 minutes at room temperature using a No. 4 spindle at 30 rpm.

As an explanation for the surprisingly good physical stability of the liquid system according to the invention, by choosing the appropriate concentration and ratio of the alkali metal silicates, the electrostatic forces between the particles, which cause the particles to agglomerate, are offset by the repulsive forces. It can be thought that there will be some surplus even if it is done. Thus, the individual particles slowly settle at a rate determined by Stokes' law. Here, at higher solids levels (> 20%), sedimentation hindrance phenomena may lead to even lower sedimentation rates. As a result, this will result in a liquid system with good physical stability.

The composition according to the invention may be used in the form of a detergent liquid cleaning product. These can be in a very wide range of specific forms depending on the intended use. These are in the form of special cleaning products, such as surgical instruments or detergents for cleaning dentures, by hand or by mechanical means, as hard surface cleaners (with or without abrasives), or instrument cleaners. It may be used as an agent (washing dishes, tableware, etc.).

A product formulated for equipment cleaning, especially for use in a dishwasher, is a preferred form of the invention.

The compositions according to the invention have improved rheology and stability compared to prior art compositions and are capable of delivering active ingredients evenly and in high doses to the machine wash cycle.

The detergent builder material is preferably a non-phosphate builder salt. Water-soluble inorganic carbonates and bicarbonates can be mentioned as such builders. Examples of water-soluble organic builders that can be used include polyacetates, carboxylates, polycarboxylates and polyhydroxy sulfonates, in which at least some proportion of the salts remain undissolved. Zeolites and amorphous silica / alumina builders are particularly preferred as builders. US Patent No. 2,
Zeolite-type aluminosilicates described in 882,243 (Union Carbide) or amorphous-type aluminosilicates described in EP 0097512 (Uniriver) may be prepared. The aluminosilicate is preferably of the formula: 0.8-
_{1.5Na 2 O; Al 2 O 3} ; 1.7~3.0SiO 2; 2~6H 2 O.

Examples of other suitable builders include NTA, EDTA, CMOS and DPA.

Regarding the weight ratio of the total composition, the builder is 5 to 60%,
Most preferably, it is 20-40%.

The second essential component of the present invention is a silicate material. When combined with an alkaline material, disilicates are particularly preferred and metasilicates may be included. The alkali metal silicate used serves as a corrosion inhibitor, protecting the metal and ceramic surfaces from the harsh alkaline environment present during the dishwashing cycle.

By weight of the total composition, the silicate-based material is 3-40%, most preferably 5-20%.

In the broadest sense, the present invention comprises compositions that do not necessarily contain detergent surfactants. In the absence of such a surfactant, the composition is used to deliver caustic to the wash liquor during mechanical dishwashing operations. However, it is usually preferred to include one or more detergent surfactants. Generally, they are selected from one or more of nonionic, anionic, cationic, zwitterionic and amphoteric surfactants. Such surfactants are commercially available and will be familiar to those skilled in the art. For example, they can be found in literature such as Schwar
“Surface Active Agents a by z, Perry and Berch
nd Detergents ", Volume I and Volume II. Preferably, the detergent active material comprises one or more nonionic agents, such as alcohols and alkylphenols having 8 to 16 carbon atoms. It includes condensation products with alkylene oxides, including ethylene oxide, propylene oxide, butylene oxide and mixtures thereof, Preferably the alcohol is linear and has 12 to 15 carbon atoms, It is condensed with 10 moles of ethylene oxide, most preferably those compounds which are generally regarded as "low-foaming", especially those in which the alkylene oxide chain terminates in a radical different from hydrogen.

The composition according to the invention may be prepared by mixing various ingredients.

Conventional additives such as colorants and fragrances may be present in the composition in conventional amounts.

Cups of tea, coffee and other food stains,
Alkali metal hypochlorite may be present in the formulation as a remover for removal from basins, pans and the like. A bleaching source may be present in the mixture in the range 0.1 to 10% by weight, most preferably in the range 0.1 to 2% by weight (percentage as active chlorine).

Electrolytes such as NaCl, Nal, Na ₂ SO ₄ may be included in the composition at 0.1-10% by weight.

An antifoaming agent may be included in the composition. These defoamers may be conventional, slightly soluble alkyl carboxylates, alkyl phosphates, hydrophobic silicas, silicon defoamers, or others. In addition to being an effective defoamer, it must be stable to hypochlorite. The defoamer can optionally be added to the composition at 0-5% by weight, more preferably 0.1-1% by weight, most preferably 0.1-0.5% by weight.

The composition according to the invention exhibits a high degree of stability at room temperature compared to other systems. Unlike known liquids, the products made according to the present invention do not require shaking to redisperse the ingredients. Moreover, the composition formulated according to the present invention has a higher density (1.
7-1.8). This is especially important when it comes to transportation. More concentrated liquids have the advantage of lower packaging and shipping costs. Similarly, it provides more active ingredient per unit dose than products made according to the prior art.

The absence of network formation due to the presence of decohesive forces within the system also had a significant effect on the properties of the product before use. That is, the liquid system according to the present invention does not easily solidify even after storage. Even after long storage
The product did not solidify and no solidification was observed. Liquid products with external structuring agents currently in circulation require shaking and squeezing bottles, whereas this product can be applied and used without doing so. 1.5
This is a convenient and advantageous aspect of this product when dealing with ~ 2.5Kg bottles.

The composition of the invention provides a liquid system which is very convenient to the consumer, while also being perfectly suitable for automatic metering applications.
The principle of automatic weighing can be used for household as well as for industrial dishwashers.

Unlike the prior art compositions, the composition according to the invention
It can be poured from a cradle without the need for shear thinning. The behavior of the dispenser is largely determined by the rheological properties of the liquid. In the prior art, Newtonian liquids are not considered suitable. Some of the liquids according to the invention were tested in order to measure the leakage in the dispenser cup of the many commercially available dispenser types. The degree of dispenser cup leakage was found to be acceptable if the liquid had a viscosity of at least 200 mPAS.

The metering of commercially available dishwasher liquids utilizes bottles with small openings to achieve high shear rates for breaking the network. Since the liquid system according to the invention is quasi-Newtonian, this high shear rate mode is not necessary during metering, so that a wide range of bottles can be selected. For this reason, if desired, equipped with an automatic ejector, for example 0.5-1.0 cm in diameter
Wide conventional spouts may be used for bottles containing the liquid system according to the invention. Since there is no need to shake, squeeze or squirt the bottle, less spillage is required, optimal weighing is achieved and less unwanted skin contact.

Dishwashing compositions formulated according to the present invention are less prone to producing spots on glass than other conventional (eg, polymer or clay) structured liquid detergent systems. This is especially noticeable after several washing cycles.

When considering systems containing zeolites as builders, the system according to the invention allows further uses. Prior art zeolite slurries are known to be unstable.
The liquid system of the present invention provides a stable zeolite slurry that does not separate upon standing. This slurry can be spray dried as a base for powder formulation, for example for textile or appliance cleaning.

The invention will now be further illustrated by the following non-limiting examples. In these examples all percentages are given by weight unless otherwise stated.

Examples 1.1.-1.3 Using 40% zeolite and 20% disilicate base compositions, the viscosities of the various compositions were measured with the addition of various amounts of KOH. For each system, viscosity was measured in terms of shear rate.

With the addition of KOH to reduce the silicate ratio, the composition exhibits quasi-Newtonian behavior. If KOH is not added,
The liquid is shear thinning.

Examples 2.1.-2.3 Logarithmic viscosities were measured as a function of logarithmic shear rate using a base composition of 20% disilicate and 10% KOH and varying the amount of zeolite added to the system.

Viscosity increases with the addition of zeolite, but does not show pseudo-Newtonian behavior.

Example 3 The stability of the liquid composition according to the present invention was measured as the percent separation at 1, 2, 3 and 4 weeks after storage at 20 ° C.

Example 4 Various compositions formulated according to the invention were used to measure the formation of spots on glass in several washes. A comparison was made with a commercially available polymer structured dishwasher liquid.

The generation of spots in four washes is measured as the number of spots on the glass cup as follows: 0 1 1-5 2 6-10 3 11-20 4> 20 5 Bauknecht GS 870 S machine 30 with standard 55 ° C program
Washing was performed at a dose of g / machine.

(Water 15 ° French hardness) The average score for 20 cups was given.

The formation of spots is considerably reduced with the composition formulated according to the invention as compared to a composition which is "externally" structured.

The following composition was prepared.

% By weight zeolite 42 sokalan 5 polymer (20% slurry) disilicate (ratio 2.0) 20 KOH (85% solution) 5 HOCL (as Cl ₂ ) 1 water Add water to make 100 composition It turns out that they won't be separated for a week,
It was suitable for washing dishes in the dishwasher.

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Claims (6)

[Claims] 1. (a) Zeolites, amorphous silica / alumina, carbonates, bicarbonates, polyacetates, carboxylates, polycarboxylates, polyhydroxy sulphonates and their presence in at least partly insoluble form. In an automatic dishwasher containing 5 to 60% by weight of a detergent builder selected from the group consisting of mixtures, (b) 3 to 40% by weight of alkali metal silicates, and (c) water up to 100% by weight. A stable and viscous liquid detergent composition suitable for use, said composition comprising an effective amount of an alkali metal hydroxide such that the alkali metal silicate has a silica to alkali ratio of 0.6 to 1.9. , Not having shear thinning properties over a range of shear rates of ¹ to 100 sec ^-1 , having a thixotropic index of 2.5 to 0.5, and imparting structure to the liquid in a suitable amount within the liquid. Said composition characterized in that it is essentially free of external network-forming structuring agents selected from loose clays, polymers or biocellulosic materials. 2. The stable liquid composition according to claim 1, wherein the amount of alkali metal hydroxide is in the range of 4.25 to 20% by weight. 3. The stable liquid composition according to claim 1, wherein the composition further contains 0.1 to 10% by weight of an alkali metal hypochlorite bleach, expressed as active chlorine. object. 4. The stable liquid composition according to claim 1, wherein the detergent builder is an aluminosilicate. 5. A stable liquid composition according to any one of claims 1 to 4, characterized in that the composition further comprises 0.1 to 10% by weight of electrolyte. 6. The stable liquid composition according to claim 1, wherein the composition has a thixotropic index of 1.5 to 0.8.