RU2278896C2 - Improved detergent composition - Google Patents

Abstract

FIELD: detergents, chemical technology.

SUBSTANCE: invention relates to the detergent composition molded by pouring from the melt. The composition comprises less 30% of solid substances and shows the fluidity limit value above 75 kPa in the range of temperatures from 20°C to 40°C and comprises the following components, wt.-%: soap based on saturated fatty acids and comprising one or some salts of (C₆-C₂₄)-fatty acids, 2-50; non-soap detergent, 2-40; water, 30-80, and optionally one or some liquid useful agents. The composition has no the pure lyotropic mesomorphic phase in the range of temperatures 20-100°C, and composition forms isotropic liquid phase or dispersion of lyotropic mesomorphic phase in the continuum of isotropic liquid in the range of temperature from 40°C to 100°C. The composition comprises less 5 wt.-% of alcohols, propylene glycol and other polyols and less 1 wt.-% of insalting electrolytes. Method for preparing the solid composition comprises preparing the melt of the detergent composition, pouring melt into form suitable for preparing the required configuration and cooling of the form or its abandonment for cooling. Invention provides enhancing hardness and improvement of consumers' properties.

EFFECT: improved preparing method, improved properties of composition.

6 cl, 3 tbl, 15 ex

Description

This invention relates to solid melt-molded detergent compositions with a solids content of less than 30% and a very high content of water or liquid beneficial agents, but nonetheless having high hardness and good consumer properties.

Pieces of detergent are usually produced in one of two ways: (i) shear-working / homogenizing the composition, followed by extrusion and stamping, or (ii) casting.

In the manufacture of bulk detergent by shear and extrusion shearing, the amount of water that can be added to the formulation is usually less than 15%. These systems are multiphase composites that belong to the type of bar "suspended in mortar" morphology. "Bars" are solid particles which, in the case of toilet soap, are crystalline salts of long chain saturated fatty acids, inorganic particles, and the like. "Mortar" is a mixture of various lyotropic liquid crystalline or isotropic liquid phases, including water, liquid additives and relatively water-soluble soaps or surfactants. These compositions typically contain 40-60% solids, 20-50% lyotropic liquid crystal phases and up to 10% isotropic liquid.

In the production of detergent compositions by injection molding, the recipe system is brought to a liquid state by raising the temperature, poured into molds and cooled. This technology is usually used to produce transparent pieces of detergents for personal use, which typically contain, along with other ingredients (such as soap and synthetic surfactants) 15-50% of expensive alcoholic ingredients, such as ethanol, polyols, sugars etc.

US Pat. No. 4,165,293 (Amway, 1979) and International Publication No. WO 96/04361 (P&G, 1996) disclose a solid, clear, lumpy detergent containing soap, synthetic surfactants, and a water-soluble organic solvent, such as, for example, propylene glycol. . The water content in these compositions is 10-32%.

The problem that arises in the production of opaque lumpy detergents by casting is that conventional compositions do not form liquids that flow at elevated temperatures. US Pat. No. 5,340,492 (P&G, 1994) discloses a composition that can be molded, including neutralized crystalline carboxylic acids (soap), synthetic surfactants, and a large amount of water and other liquids. The compositions obtained according to US patent No. 5340492, are soft, have a yield strength of less than 75 kPa (measured using a device with a wire for cutting cheese) and, therefore, are unsuitable for use as solid pieces of toilet soap, which should be sufficiently rigid, to make them comfortable to hold in use.

In order to increase the hardness of the detergent bar in the examples described in the patent, ingredients such as polyols (for example propylene glycol) are used in the compositions under the guise of the so-called “product appearance enhancers”. This patent does not disclose a single composition that does not include “appearance enhancing agents” when synthetic surfactants are present in the composition. These "appearance enhancing agents" are very expensive, reduce the amount and rate of formation of soap suds and, moreover, they are well known in the prior art (US Pat. No. 4,165,293, published international application WO 96/04361).

Another application by the same authors, considered simultaneously with this one, describes that the introduction of small amounts of salting electrolytes into fusible washing compositions for casting, consisting of fatty acid soap, an active detergent, a very large amount of water or liquid beneficial agents, results in solid products able to maintain a certain shape, with a yield strength of more than 75 kPa (which was measured using a device with a wire for cutting cheese). These compositions can be held in hands, they are economical, foam well and have good consumer properties.

The fatty acid soap of this application is one or more neutralized C ₆ -C ₂₄ fatty acids.

Prior art publications typically report the use of additives, for example polyols or salting electrolytes or other “appearance enhancing agents” in melt-molded compositions containing fatty acid soap, an active detergent, very large amounts of water or liquid beneficial agents to increase the rigidity of the product.

It is now possible to obtain detergent compositions without additives or with very small amounts of additives by melt casting, the solids content of these compositions being less than 30%, they contain a large amount of water or other liquid agents and have a yield strength of more than 75 kPa in the temperature range from 20 up to 40 ° C.

In a first embodiment, the invention includes a melt-molded detergent composition, which is preferably a bulk detergent with a solids content of less than 30% and a yield strength of more than 75 kPa in the temperature range of 20 to 40 ° C., comprising:

(a) 2-50 wt.% soap from saturated fatty acids containing one or more salts of fatty C ₆ -C ₂₄ acids,

(b) 2-40 wt.% particles of active detergent,

(c) 30-80 wt.% water and optionally other liquid beneficial agents,

characterized in that in this composition a pure lyotropic liquid crystal phase is not detected in the temperature range from 20 to 100 ° C, but an isotropic liquid phase or dispersion of the lyotropic liquid crystal phase in a continuous medium of an isotropic liquid is formed in the temperature range from 40 to 100 ° C.

According to a more preferred aspect of the present invention, there is provided a melt-cast lumpy detergent composition with a solids content of less than 30%, which is free of additives and has a yield strength of more than 75 kPa in the temperature range of 20 to 40 ° C., comprising:

(a) 2-50 wt.% soap from saturated fatty acids containing one or more salts of fatty C ₆ -C ₂₄ acids,

(b) 2-40 wt.% particles of active detergent,

(c) 30-80 wt.% water and optionally other liquid beneficial agents,

characterized in that in this composition a pure lyotropic liquid crystal phase is not detected in the temperature range from 20 to 100 ° C, but an isotropic liquid phase or dispersion of the lyotropic liquid crystal phase in a continuous medium of an isotropic liquid is formed in the temperature range from 40 to 100 ° C.

The additives that are commonly used in the prior art are ethanol, propylene glycol and other polyols, salting electrolytes, and the like. According to the invention, it is preferable to avoid the use of any of these additives in the compositions.

More specifically, in the detergent composition of this invention, preferably solvent alcohols are absent, and also preferably polyhydric alcohols are absent. In this context, “absent” means that the composition contains less than 5 wt.%, More preferably less than 1 wt.%, Even more preferably less than 0.5 wt.% Polyhydric alcohols, and may even not contain these substances.

In addition, salivating electrolytes are preferably absent in the compositions of this invention; this means that they contain less than 1 wt.%, more preferably less than 0.5 wt.% of salting electrolytes and may not contain them at all. Preferably, soap (fatty acid salts) is not the predominant active detergent of the composition.

The presence of an isotropic liquid phase and liquid crystal phases in surfactant systems is preferably determined using optical polarization microscopy. Liquid crystalline phases are anisotropic in nature, which makes the refractive index dependent on orientation. In general, such birefringent systems change the plane of polarization of polarized light. An isotropic liquid appears black between intersecting polarizers, but the liquid crystal system is more transparent, for example, in the lamellar (layered) liquid crystal phases, textures such as the Maltese cross or a “vein of oil” (similar to a large loop) are found, while non-geometric fan-like textures appear in the hexagonal phases . The characteristic textures of various lyotropic liquid crystalline phases and their dispersions are described in the literature.

According to another aspect of the present invention, there is provided a method of manufacturing a solid formed detergent composition according to this invention, comprising the steps of:

a) preparing a melt of the above composition,

b) pouring the above melt into the mold to obtain the product of the desired configuration,

c) cooling the mold with the melt in a stationary position to cause solidification of the melt. According to a preferred aspect of the invention, there is provided a method of manufacturing a solid molded packaging of a detergent composition, comprising the steps of:

a) preparing a melt of the above composition,

b) pouring the aforementioned melt into a polymer prepared in advance to obtain a product of the desired configuration

c) sealing the mold and

d) cooling the mold with the melt in a stationary position to cause solidification of the melt.

This invention relates to detergent compositions, which essentially have special phase characteristics, which results in a melt-formed piece with a solids content of less than 30% and a very high content of water or other liquid beneficial agents. The washing composition is characterized in that it does not show a pure lyotropic liquid crystal phase in the temperature range of 20-100 ° C and this composition forms an isotropic liquid phase or dispersion of the lyotropic liquid crystal phase in a continuous medium of an isotropic liquid in the temperature range from 40 to 100 ° C.

The presence of an isotropic liquid crystalline phase and liquid crystalline phases in surfactant systems is preferably determined by optical polarization microscopy. The liquid crystal phases are inherently anisotropic, which makes the refractive index dependent on orientation. In general, such birefringent systems change the plane of polarization of polarized light. An isotropic liquid appears black between intersecting polarizers, but the liquid crystal system is more transparent, for example, in the lamellar (layered) liquid crystal phases, textures such as the Maltese cross or a “vein of oil” (similar to a large loop) are found, while non-geometric fan-like textures appear in the hexagonal phases . You can observe several textures in the same phase structure.

Characteristic textures of various lyotropic liquid crystalline phases (and their dispersions) are described in the following publications: (i) "The Aqueous Phase Behavior of Surfactants" by Robert G. Laughlin, Academic Press, New York, 1994, Pages 538-542. (ii) "The Colloidal Domain Where Physics, Chemistry, Biology, and Technology Meet" by D. Fennel Evans, Hakan Wennerstrom, VCH Publishers, New York, 1994, Pages 251-252.

Solid shaped articles of the composition of the present invention are rigid enough to be comfortable to hold, economical, foam well and have good consumer properties. The yield strength for these compositions exceeds 75 kPA according to measurements using an automatic penetrometer.

Soaps based on saturated fatty acids are preferably selected from one or more salts of C ₆ -C ₂₄ saturated fatty acids. The soap used may be sodium, potassium, magnesium, aluminum, calcium or lithium salt of saturated fatty acids. Especially preferred is soap obtained in the form of a sodium or potassium salt of a saturated fatty acid.

The content of saturated fatty acid based soaps in the composition is preferably 5-50 wt.% And more preferably 5-40 wt.%.

The compositions of this invention also include active detergents, which may be soap based or non-soap. It is preferable to use non-soap active detergents that are selected from anionic, nonionic, cationic, amphoteric or zwitterionic surfactants (surfactants) or mixtures thereof.

Acceptable anionic active detergents are water-soluble salts of organic sulfuric acid reaction products having in their molecular structure an alkyl radical containing from 8 to 22 carbon atoms, and the radical is selected from sulfonic or sulfuric acid ester radicals and mixtures thereof. Some examples of synthetic anionic active detergents are linear alkylbenzenesulfonate, sodium lauryl sulfate, sodium sulfate lauryl ether, alpha olefin sulfonate, alkyl sulfate ether, fatty sulfonic acid methyl ester, alkyl isothionate, and the like.

The cations most suitable for the above types of active detergents are sodium, potassium, ammonium and various amines, for example, monoethanolamine, diethanolamine and triethanolamine.

Compounds acceptable as non-ionic active detergents can be broadly described as compounds obtained by condensation of alkylene oxide groups that are hydrophilic in nature, with any organic hydrophobic compound, which may be aliphatic or alkyl aromatic in nature. Typical non-ionic surfactants are the condensation products of linear or branched C ₈ -C ₂₂ aliphatic alcohols with ethylene oxide, for example, the condensation product of coconut oil with ethylene oxide, in which from 2 to 15 mol of ethylene oxide (EO) per 1 mol of coconut alcohol. Some examples of nonionic surfactants are the condensation product of alkyl phenol with EO, the condensation product of tall alcohol with 10 moles of EO, alkyl dimethyl amine oxides, lauryl mono ethanol amide, sugar esters and the like.

Examples of amphoteric active detergents are coconut amidopropyl betaine, coconut betaine, and the like.

Active cationic and zwitterionic detergents may also optionally be included in the compositions of this invention.

Further examples of acceptable types of active detergents are provided in the following link: "Handbook of Surfactants", M.R. Porter, Chapman and Hall, New York, 1991.

The active detergent for use in the detergent composition of this invention is preferably anionic and is usually up to 40% or more, preferably 2 to 30%.

According to a preferred aspect of the present invention, liquid substances useful to the skin are added to the composition, such as moisturizers, emollients, sun protection products and anti-aging skin products. Examples of humectants and wetting agents include polyols, glycerin, cetyl alcohol, Carbopol 934, ethoxylated castor oil, paraffin oils, lanolin and its derivatives. You can also include organosilicon compounds, for example, silicone surfactants (surfactants), such as DC3225C (Dow Corning) and / or silicone softeners, silicone oil (DC-200 Ex-Dow Corning). Sun protection products, for example 4-tert-butyl-4'-methoxybenzoylmethane (available under the trade name Parsol 1789 from Givaudan) and / or 2-ethylhexylmethoxycinnamate (available under the trade name Parsol MCX from Givaudan) or other UV- A and UV-B are also administered. Other skin-friendly agents, for example polyethylene glycol (PEG), can also be incorporated into the composition.

Other optional ingredients, such as salting electrolytes, polyols, hair conditioners, fillers, coloring matter, perfume, opacifying agent, preservatives, one or more water-insoluble bulk solids, such as, for example, talc, kaolin, polysaccharides and others conventional ingredients can be incorporated into the composition, although it is preferred if polyols and salting electrolytes are not present in the composition.

The preferred method according to this invention may be a method for producing a melt of a washing composition consisting of 2-50 wt.% Soap based on saturated fatty acids, 2-40 wt.% Non-soap active detergent and 30-80% water or other liquid useful agents, the fact that a composition is obtained in which a pure lyotropic liquid crystal phase is not detected in the temperature range of 20-100 ° C, and this composition forms an isotropic liquid phase or a dispersion of the lyotropic liquid crystal phase in a continuous medium of an isotropic liquid in temperature range from 40 to 100 ° C. In this method, the melt is poured into any suitable shape or into a pre-prepared polymer mold to obtain the desired configuration, the mold is tightly closed and cooled in a stationary state to cause solidification.

The shape can be selected accordingly to get a piece of almost final configuration or to get bars / blocks. These bars / blocks can be subjected to additional molding to obtain products - detergents.

If a solid detergent composition is produced using a thermoformed polymer mold of an almost final configuration; the mold is tightly sealed to obtain a castable detergent composition in the package.

The invention will now be illustrated by the non-limiting examples presented below.

EXAMPLES

Example 1

Screening of compositions regarding their phase characteristics

The composition according to this invention is characterized in that it does not show a pure lyotropic liquid crystal phase in the temperature range from 20 to 100 ° C, and the composition forms an isotropic liquid phase or dispersion of the lyotropic liquid crystal phase in a continuous isotropic liquid in the temperature range from 40 to 100 ° C . Comparative examples of this invention and beyond the scope of this invention are presented in table 1.

but. Phase characteristic:

Determination of the phase characteristics of the composition is carried out using optical polarization microscopy. A drop of the melt of the composition at an elevated temperature (about 80 ° C) is transferred to a microscope slide and covered with a coverslip. The edges of the coverslip are glued with UV glue to minimize moisture loss. A glass slide is lifted onto a microscope stage equipped with an adjustable heating-cooling device. The system is heated to 110 ° C with a heating rate of 1 ° C per minute. The temperature at which an isotropic liquid phase or its dispersion, or a pure liquid crystal phase, is recorded.

The system is then cooled to cause solidification at a rate of 1 ° C. per minute to check if pure liquid crystalline phases are formed during cooling. Lyotropic liquid crystal phases are basically anisotropic, which makes the refractive index dependent on orientation. In general, such birefringent systems change the plane of polarization of polarized light. An isotropic liquid appears black between intersecting polarizers, but the liquid crystal system is more transparent, for example, textures such as the Maltese cross or “vein of oil” (similar to a large loop) are found in the lamellar liquid crystal phases, while non-geometric fan-like textures appear in the hexagonal phases.

You can observe several textures within the same phase structure. Characteristic textures of various lyotropic liquid crystal phases (and their dispersions) are described in the following publications: (i) "The Aqueous Phase Behavior of Surfactants" by Robert G. Laughlin, Academic Press, New York, 1994, Pages 538-542. (ii) "The Colloidal Domain Where Physics, Chemistry, Biology, and Technology Meet" by D. Fennell Evans, Hakan Wennerstrom, VCH Publishers, New York, 1994, Pages 251-252.

b. Determination of solids content:

The solids content of the detergent compositions is determined by low-field NMR using the method described in Suresh M. Nadakatti, “Modified Data Handling for Rapid Low Field NMR Characterization of Lyotropic Liquid Crystal Composites”, J. Surfactants and Detergents, Vol. 2, No. 4, pp. 515-521, 1999.

from. Obtaining pieces of the washing composition:

The melt of the washing composition at an elevated temperature of 80 ° C is poured into a rectangular shape of the following sizes: 75 mm (L) x 55 mm (W) x 40 mm (H), where L is the length, W is the width and H is the height. The compositions allow to cool to cause solidification, and get a piece of detergent composition.

d. Yield Strength Measurement:

The pieces of the detergent composition are then kept in furnaces in which the temperature is maintained at 25 ° C and 40 ° C, respectively, for 4 hours and left to come into equilibrium. The yield strength of the pieces at 25 ° C and 40 ° C is measured using an automatic penetrometer according to the procedure described below.

The automatic penetrometer used to determine the yield strength is the PNR 10 model manufactured by M / s Petrotest Instruments GmbH. For measurements using a standard cone (Hollow Cone) (part # 18-0101, according to ASTM D 217-IP 50) together with a plunger (Plunger) (part # 18-0042). The cone consists of a conical main body made of brass with a removable tip made of hardened steel. The total mass of the cone was 102.5 g. The total mass of the moving plunger was 47.5 g. The total mass of the cone and plunger that falls on a piece of the washing composition is therefore 150 g. Additional weights of 50 g and 100 g are also used ( they bring the mass falling on the sample to 200 and 250 g, respectively). The yield strength of the sample at 25 ° C and 40 ° C is measured by a standard method, which includes the following stages:

1. A piece is placed on the penetrometer table.

2. The penetrometer measuring device is lowered down so that the tip of the penetrometer touches the piece, but does not penetrate into the piece.

3. Measurement is started by pressing the "start" key.

4. The penetration depth is read in mm according to the indications on the display.

5. The measured value of the penetration depth is used to calculate the yield strength for a piece of detergent composition according to the following equation:

Yield strength = Applied force / (projected cone surface) = (m × g) × 10 ³ / [π (p tan 1/2 θ + 1/2 tip diameter) ² ],

Where

Yield strength expressed in kPa;

m represents the total mass falling on the flat surface of the piece, expressed in kg;

g represents the acceleration due to gravity, expressed in m / s ² ;

p represents the distance by which the tip of the cone penetrates into a piece of detergent in mm;

θ is the angle of the cone (30 °);

The diameter of the end of the cone is 0.359 mm.

According to the above equation, the yield strength of a piece of detergent is greater than 75 kPa if the measured penetration depth is less than 10 mm for a total mass of 200 g falling on the sample. Three values of yield strength are calculated for the total mass falling on a piece of detergent, equal to 150 g, 200 g and 250 g; the average of three values is used as the yield strength of a piece of detergent composition.

e. Examples of detergent lump compositions:

The data presented in table 1 show that only the composition described in example 1.1, which satisfies the phase characteristics of this invention, forms hard pieces having a yield strength above 75 kPa. The compositions described in examples 1.2 and 1.3 are soft, as they form a pure lyotropic liquid crystal phase in the temperature range from 35 to 75 ° C and do not form an isotropic liquid phase or its dispersion in the temperature range from 40 to 100 ° C. In Example 1.4, the temperature at which the isotropic phase or its dispersion forms upon heating is in the range specified in this invention, but the pure liquid crystal phase is formed upon cooling and, therefore, the bar was soft. This shows that in order to obtain hard bars with a yield strength of more than 75 kPa, it is important that both criteria of phase characteristics are satisfied.

Table 1 Components Example 1.1 Example 1.2 Example 1.3 Example 1.4 Sodium stearate fifteen fifteen 12 16,2 Sodium Lauryl Ether - 10 10 - Coconut Betaine 5 - - 10 Water 80 75 78 73.8 Is a pure liquid crystal phase found in the composition in the temperature range of 20-100 ° C? No Yes. Pure Н1 * phase (75-35 ° С) Yes. Pure Н1 * phase (75-35 ° С) Yes. Pure Н1 * phase (75-35 ° С) Does the composition form an isotropic liquid phase or a dispersion of a lyotropic liquid crystal phase in a continuous medium of an isotropic liquid in the temperature range from 40-100 ° C? Yes.
Above 65 ° C No No Yes.
Above 80 ° C Are solid crystallites found in the composition upon cooling? Yes Yes Yes Yes Solids content (%) 16.6 fifteen 13 11.7 Yield strength at 25 ° C (kPa) 266 55 54 47 H1 * is a pure hexagonal crystalline phase.

Additional examples of compositions that have phase characteristics according to this invention are shown in Table 2, and compositions with phase characteristics that do not correspond to this invention are shown in Table 3. All examples in table 2 contain less than 20% solids and, in addition, form stiff pieces with a yield strength of more than 75 kPa at 25 ° C. The examples described in table 3, on the contrary, are soft compositions.

table 2 Components Example 1.5 Example 1.6 Example 1.7 Example 1.8 Example 1.9 Example 1.10 Example 1.11 Sodium stearate - - - - 13 - - Sodium palmitate twenty eighteen - - - - - Sodium myristate - - twenty 25 6.6 - - Sodium laurate - - - 5 - 22.2 - Sodium Hydroxystearate - - - - - - 21.5 Sodium ricinoleate - - - - - - eleven Sodium Lauryl Ether - 6 - - - 5 - Sodium Lauryl Sulfate - - - - 6 - - Coconut Betaine - - 8 - - - - Alpha olefin sulfonate 8 - - 8 - - 10 Water 72 76 72 62 74,4 72.8 57.5 Is a pure liquid crystal phase found in the composition in the temperature range of 20-100 ° C? No No No No No No No Does the composition form an isotropic liquid phase or a dispersion of a lyotropic liquid crystal phase in a continuous medium of an isotropic liquid in the temperature range from 40-100 ° C? Yes.
Above 65 ° C Yes.
Above 64 ° C Yes.
Above 55 ° C Yes.
Above 55 ° C Yes.
Above 50 ° C Yes.
Above 42 ° C Yes.
Above 80 ° C Are solid crystallites found in the composition upon cooling? Yes Yes Yes Yes Yes Yes Yes Solids content (%) twenty 19,2 13.1 18.6 17.6 9 17 Yield strength at 25 ° C (kPa) 154 350 133 613 143 296 110

Table 3 Components Example 1.12 Example 1.13 Example 1.14 Sodium stearate 7.7 - - Sodium palmitate 9,4 fifteen twenty Sodium myristate - - - Sodium laurate - - fourteen Sodium Hydroxystearate - - - Sodium ricinoleate - - eleven Sodium oleate - - 18.6 Sodium Lauryl Ether 8.6 10 - Sodium Lauryl Sulfate - - - Coconut Betaine - - - Alpha olefin sulfonate - - - Water 74.3 75 36,4 Is a pure liquid crystal phase found in the composition in the temperature range of 20-100 ° C? Yes. Pure Н1 * phase (100-40 ° С) Yes. Pure Н1 * phase (up to 58 ° С) Yes. Pure Н1 * phase (up to 58 ° С) Does the composition form an isotropic liquid phase or a dispersion of a lyotropic liquid crystal phase in a continuous medium of an isotropic liquid in the temperature range from 40-100 ° C? No No No Are solid crystallites found in the composition upon cooling? Yes Yes Yes Solids content (%) 19.7 16.5 21.5 Yield strength at 25 ° C (kPa) 49 73 <15 H1 * is a pure hexagonal crystalline phase.

Example 2

The method of obtaining lumpy detergent

Based on the screening procedure described in Example 1, a fatty acid mixture corresponding to Examples 1.5 to 1.11 is placed in 2 liter round bottom flasks and mixed with a non-soap active detergent and water. The temperature of the resulting portion is raised to 80 ° C. An aqueous solution of sodium hydroxide is added to the mixture to neutralize fatty acids. A temperature of 80 ° C. is maintained in the resulting mixture, so that a pure isotropic solution is obtained. The melt of the washing composition at 80 ° C is poured into a thermoformed mold from the polymer and the mold inlet is sealed tightly. The mold is left to cool to ensure the solidification of the soap, and thus receive a piece of detergent composition in the package.

Claims (6)

1. A melt-molded detergent composition with a solids content of less than 30%, having a yield strength of more than 75 kPa in the temperature range from 20 to 40 ° C, consisting of (i) 2-50 wt.% soap based on saturated fatty acids, including one or more salts of C ₆ -C ₂₄ fatty acids, (ii) 2-40 wt.% non-soap detergent, (iii) 30-80 wt.% water and, optionally, one or more liquid beneficial agents, moreover, the composition does not show a pure lyotropic liquid crystal phase in the temperature range of 20-100 ° C, and the composition forms an isotropic liquid phase or dispersion of the lyotropic liquid crystal phase in a continuous medium of an isotropic liquid in the temperature range from 40 to 100 ° C, and the composition contains less than 5 wt. .% alcohols, propylene glycol and other polyols and less than 1 wt.% salting electrolytes. 2. The detergent composition according to claim 1, in which water and optional liquid beneficial agents are present in an amount of 60-80% of the total weight of the composition. 3. A detergent composition according to any one of the preceding claims, wherein the fatty acid soap is a sodium or potassium salt of a fatty acid. 4. The detergent composition according to any one of the preceding paragraphs, in which the liquid beneficial agent is selected from moisturizers, wetting agents, softeners, sun protection agents, and anti-aging agents. 5. A method of producing a detergent composition by melt casting according to any one of claims 1 to 4, including (i) preparing a melt of the washing composition, (ii) pouring the melt into a mold suitable to obtain the desired configuration, and (iii) cooling the mold or leaving it to cool, resulting in a solid detergent composition. 6. The method according to claim 5, in which stage (ii) comprises two substages: (iia) pouring the melt into a preformed polymer mold to obtain the desired mold configuration; and (iib) pasting the completed form, to obtain a solid detergent composition in a molded packaging.