MXPA01001588A - Multilayer detergent tablet with different elasticities - Google Patents

Abstract

The present invention relates to a detergent tablet having at least a first and a second layer, whereby the first layer is less elastic than the second layer, and if said tablet has more than two layers, the tablet is such that a less elastic layer is situated at an end of the tablet to increase the integrity and robustness of the entire tablet during production, shipping and handling while keeping substantially good dispensing properties.

Description

TABLET DETERGENT OF MULTIPLE LAYERS WITH DIFFERENT ELASTICITIES TECHNICAL FIELD The present invention relates to detergent tablets, especially those adapted for use in washing. Although cleaning compositions in tablet form have often been proposed, they have not gained (with the exception of soap bars for personal washing) any substantial success, despite the various advantages of the products in a unit supply form. . One of the reasons for this may be that detergent tablets usually dissolve slower than the constituent powders of which they are made, simply because the constituent powders are bound by force in the tablet, the water having a comparatively small opportunity to penetrate between the tablets. they. This gives rise to the problem that slowly dissolving tablets cause residues which may, for example, be visible through the washing machine door during the washing cycle, or which stick to the fabrics at the end of the washing cycle. , or both. This can be compensated by using low compression forces to maintain high porosity and good dissolution profile. However, said tablets are typically less elastic and have such mechanical characteristics that breakage is likely to occur during their production or handling.

DE-A-2 207 633, published on August 30, 1973, discloses tablets having three layers, the middle layer being interposed between two end layers, the two end layers being made to protect the intermediate layers from mechanical shocks, while allowing the dissolution of the tablet in less than one minute. However, particularly in certain front-loading washing machines, tablet waste problems that appear visibly in the washing machine window have still been encountered. In fact, in particular for detergent tablets, dissolution problems are particularly acute, due for example to the tendency of gelling of the surfactant materials, or to the low level of water used for environmental reasons, or due to the low dissolution. temperature, etc. The object of the present invention is to provide tablets formed by compressing a material formed of particles, the material formed of particles comprising a surfactant, the tablet being suitable for storage, shipping and handling without breaking while dissolving easily and quickly in washing solution. , releasing the active ingredients in the washing solution and disintegrating and completely dispersing in alkaline solutions or solutions rich in surfactant such as the washing solution.

BRIEF DESCRIPTION OF THE INVENTION The object of the invention is achieved by providing a detergent tablet having at least a first and a second layer, wherein the first layer is less elastic than the second layer, and if said tablet has more than two layers, the tablet is such that a less elastic layer is located at one end of the tablet.

DETAILED DESCRIPTION OF THE INVENTION Figure 1 shows two typical profiles to measure the elasticity of a layer or a tablet, the profile representing the load applied to the tablet or layer, corresponding to the strength of the tablet or layer, depending on the displacement of the load to the length of the main axis of the tablet or layer. A curve is shown which corresponds to a more elastic tablet or layer and to a less elastic tablet or layer, together with schemes showing the structural changes to which the tablet or layer is subjected during the measurement. Figure 2 represents a typical profile for measuring the elasticity of a layer or tablet, the profile representing the load applied to the tablet or layer, which corresponds to the strength of the tablet or layer, as a function of the displacement of the load to along the main axis of the tablet or layer. The breaking point that gives the maximum height H of the curve has been marked, as well as the area A under the curve taken from the point of rupture, whereby the elasticity is derived from this by dividing A by H. The present invention relates to a detergent tablet. By detergent, it is understood that the tablet comprises surfactants. A tablet having a height along a main axis and a cross section normal to the main axis is defined, the cross section preferably being substantially constant when traveling along the main axis, the tablet having two ends, each end being located at each end of the main axis, and having a surface area substantially equal to the cross section of the tablet. The tablet is such that it comprises at least a first and a second layer. Normally, these layers are produced by compressing particulate materials. The composition of these layers may be similar or different, and the compression force used to form these layers may also be similar or different. It should be noted that a preferred embodiment of a tablet according to the invention comprises only two layers, but tablets with more layers can be considered. According to the invention, a layer is preferably a part of a tablet obtained by compressing particulate materials, this part of the tablet having a height along the main axis of the tablet, and a cross section corresponding to the cross section of the tablet. the tablet, so that the composition or the physical and mechanical characteristics of this part differ from the rest of the tablet. In other words, a tablet according to the invention is obtained by stacking layers along the main axis to form the tablet, these layers adhering to each other to form the tablet, the adhesion between the layers being provided by mechanical or chemical means. Considered independently, each layer can be considered as a single-layer tablet, in terms of composition, for example. According to the invention, the first layer is less elastic than the second layer. For less elastic, it should be understood that the elasticity is less than the elasticity of the second layer. When more than two layers are present in the tablet, a less elastic layer is simply a layer so that there is another layer in the tablet which is more elastic. In other words, if three layers are present with gradual and different elasticity, there are two less elastic layers. According to the invention, the less elastic layer is the most brittle layer between all the layers in the tablet. For the purposes of the invention, brittle should be understood as opposed to elastic. The same applies for more elastic, that is, less brittle, or more elastic, that is, less brittle. Typically, the less elastic layer has an elasticity 10% less than the elasticity of a more elastic layer of the same tablet, preferably 20% smaller, more preferably 30% smaller, even more preferably 40% smaller, and most preferably 50% smaller . In accordance with the invention, the elasticity-fragility scale is measured by the elasticity of the tablet. According to the invention, if said tablet has more than two layers, the tablet is such that a less elastic layer is located at one end of the tablet. The less elastic layer is not necessarily the least elastic layer. In a preferred embodiment, the less elastic layer is located at one end. This is beneficial for dissolution, because the surface activity of this less elastic layer is high because it is exposed since it is located at one end. Of course, according to the invention, the mechanical properties and dissolving properties of an individual tablet can be made more independent of one another, so that a more elastic layer will more specifically provide mechanical integrity and protection, whereas a less elastic layer will more specifically favor a fast and efficient dissolution. In fact, a less elastic layer and therefore more brittle, will quickly disperse in solution. The level of elasticity of the different layers can be adjusted using different parameters, such as different chemical composition or different understanding strength. In particular, if different compositions are used, one layer may comprise more binders than another which will become more elastic, that is, less brittle. It should be noted that it is preferred that a less elastic layer comprises higher levels of surfactant by weight. Of course, a less elastic layer will dissolve more quickly, and will therefore compensate for the gelling of the surfactants because of their brittleness. In fact, the gelling of the surfactant hinders rapid and effective dissolution, which can be compensated for by concentrating said surfactants in a less elastic layer. This can be advantageously combined with the use of highly soluble compounds, hydrophobic compounds and compounds that provide high cohesive effect by virtue of minor understanding, for example. In another preferred embodiment and in a two-layer tablet according to the invention, the tablet is such that the more elastic layer is located at one end of the tablet. Of course, it was found that it is sufficient to have a less brittle layer have good mechanical characteristics at one end of the tablet. This particularly applies to the method for obtaining a tablet according to the invention, whereby the less brittle, ie more elastic layer of the tablet is placed at the lower end of the tablet during production. Even more preferably, the less brittle, ie more elastic, layer is placed on the lower end of the tablet during its production. Of course, mechanical stress is particularly high during production, and almost only the lower end of the tablet is exposed to mechanical constraints at this stage. In addition, this allows obtaining good mechanical strength, while allowing a more brittle layer to be placed on the other end of the tablet, whereby this more brittle layer will benefit from a larger contact surface with the solution when the tablet is dissolved in solution. It was found that said mechanical strength improves when a tablet having a substantially rectangular cross section is used. Of course, the strength of the tablet could be improved to a constant compression value by using a rectangular tablet. At equal weight, equal compression force, equal composition, equal height and equal volume, a rectangular tablet has significantly improved mechanical strength when compared to round tablets. This applies particularly to square tablets. A layer may preferably have a height that varies between 5 and 95% of the total height of the tablet. More preferably, the more elastic the tablet is, the thinner it is to have a minimal impact on the general dissolution of the whole tablet. In a preferred embodiment, a tablet according to the invention will comprise layers having different hardness (or softness), whereby its resistance to tension will be different. Preferably, the tablet will comprise a softer layer having a tensile strength between 5 and 100 kPa, as well as a harder layer having a tensile strength between 5.5 and 150 kPa. In a preferred embodiment according to the invention, the tablet comprises at least two layers having different elasticity, the harder layer being more resistant to mechanical shocks, and the softer layer having better dissolution characteristics. In a more preferred embodiment according to the invention, a more brittle layer is also a softer layer, and a more elastic layer is also harder. However, this may not be the case.

Elasticity The elasticity of a tablet or a layer of a tablet is evaluated as follows: 1. A load is pressed flat on one end of the tablet or layer for which the elasticity is tested, the load being pressed along the direction of the main axis of the tablet or layer. 2.- The force by the load is measured as a function of the displacement of the load. 3.- Two possible curves obtained by this method are illustrated in figure 1. "These two curves show the type of curves obtained for two different tablets or layers, one of the tablets being more elastic than the other, which at its time is more brittle (= less elastic). The elasticity value corresponding to the tablet or layer tested is derived from this experimental curve in the following way: The area under the curve and beyond the breaking point is calculated by integrating the curve from its maximum value to large displacement values. This area A is then divided between the height H of the curve at the point of rupture to normalize the elasticity of the tablet or layer, E.

This is illustrated in Figure 2. High values for E represent high elasticity, while low values represent highly brittle layers or tablets. To carry out this test, the following equipment was used: • Instron 4444 machine with a standard 2kN load cell linked to a normal PC computer. The program used to make the calculations was a Series IX version 7.49.00 provided by the equipment supplier. • A Plexiglas cylinder, 25 mm in diameter, 30 mm in height and weighing 18 g, was used to crush the tablet or layer. • A standard die for making tablets or layers, this die having a diameter of 54 mm. • The tablet or layer is placed between the plates of the Instron 4444, and the Plexiglas cylinder is placed in the middle of the end of the tablet or layer. • The cross head of the load cell moves at a constant speed of 10 mm / min, and the computer initiates the recording of the tablet's resistance force against the displacement of the cylinder in the tablets. • The elasticity is calculated by dividing the area under the slope after the point of rupture between its maximum height (see figures and previous explanations). • Elasticity is measured in this way in J / kN (Joules for the area, and kN for the maximum height used to normalize the area curves).

• Typically, the elasticity value for a preferred embodiment of the tablets according to the invention, and more particularly adapted for use in laundry, is comprised between 0.5 and 5 J / kN, and more preferably between 1 and 4 J / kN . It is preferred that a more elastic layer or tablet for use in laundry, for example, have an elasticity comprised between 3 and 4J / kN, more preferably between 3.1 and 3.5 J / kN. It is preferred that a more brittle layer or tablet for use in laundry, for example, have an elasticity comprised between 1.5 and 2.5 J / kN, more preferably between 1.7 and 2.1 J / kN.

Highly soluble compounds In a preferred embodiment, the tablet preferably comprises a highly soluble compound. More preferably, this compound is formed or is present at higher levels by weight in the relatively elastic layer of the tablet, i.e., the less brittle layer, to favor further dissolution. Of course, it may be preferred to facilitate the dissolution of the more elastic layer, since this layer will be more compressed, for example, in a more brittle layer. Said compound could be formed from a mixture or a single compound. A highly soluble compound is defined as follows: A solution is prepared in the following manner comprising deionized water as well as 20 grams per liter of a specific compound: 1- 20 g of the specific compound is placed in a Sotax beaker. This beaker is placed in a bath at a constant temperature set at 10 ° C. An agitator with a marine impeller is placed in the beaker so that the bottom of the agitator is 5 mm above the bottom of the Sotax beaker. The mixer is adjusted to a rotation speed of 200 revolutions per minute. 2- 980 g of the deionized water are introduced into the Sotax beaker. 3-10 s after the introduction of water, the conductivity of the solution is measured, using a conductivity meter. 4- Step 3 is repeated after 20, 30, 40, 50, 1 min, 2 min, 5 min and 10 min after step 2. 5- The measurement taken at 10 min is used as the plateau value or maximum value . The specific compound is highly soluble according to the invention when the conductivity of the solution reaches 80% of its maximum value in less than 10 seconds, starting from the complete addition of the deionized water to the compound. In truth, by monitoring the conductivity in this way, the conductivity reaches a plateau after a certain time, this plateau being considered as the maximum value. Said compound is preferably in the form of a flowable material consisting of solid particles at temperatures between 10 and 80 ° Celsius for ease of handling, but other forms such as a paste or a liquid can be used. Examples of highly soluble compounds include sodium diisoalkylbenzene sulfonate or sodium toluene sulfonate.

Cohesive effect In a preferred embodiment of this invention, the tablet preferably comprises a compound having a cohesive effect on the particulate material of a detergent matrix forming the tablet. More preferably, this compound is formed or is present at higher levels by weight in the relatively elastic layer of the tablet, i.e., the less brittle layer, to obtain satisfactory brittleness without the need for high compression. The cohesive effect on the particulate material of a detergent matrix forming the tablet or a layer of the tablet is characterized by the force required to break a tablet or layer based on the examined detergent matrix pressed under conditions of controlled compression. For a given compression force, a high tablet strength indicates that the granules remained more tight when they were compressed, so that a strong cohesion effect is taking place. Means to evaluate the resistance of the tablet or layer (also called diametral fracture effort) are provided in Pharmaceutícal dosage forms: tablets volume 1 Ed. H.A. Lieberman et al, published in 1989.

The cohesive effect is measured by comparing the strength of the tablet or layer of the original base powder without compound having a cohesive effect, with the strength of the tablet or layer of a powder mixture comprising 97 parts of the original base powder and 3 parts of the original base powder. compound that has a cohesive effect. The compound having a cohesive effect is added to the matrix in a form in which it is substantially free of water (water content below 10% (preferably below 5%)). The temperature of the addition is between 10 and 80 ° C, more preferably between 10 and 40 ° C. A compound is defined as having a cohesive effect on the particulate material according to the invention when at a given compaction force of 3000 N, tablets with a weight of 50 g of detergent particulate material and a diameter of 55 mm have its tablet elasticity increased by more than 30% (preferably 60 and more preferably 100%) by the presence of 3% of the highly soluble compound having a cohesive effect on the base particulate material. An example of a compound having a cohesive effect is sodium diisoalkylbenzenesulfonate. It was found that by integrating a highly soluble compound having a cohesive effect on the particulate material according to the invention to a tablet formed by compressing a particulate material comprising a surfactant, the solution of the tablet in an aqueous solution was increased in a significative way. In a preferred embodiment, at least 1% by weight of the tablet is formed of the highly soluble compound, preferably at least 2%, more preferably at least 3%, and more preferably at least 5% by weight of the tablet being formed from the highly soluble compound having a cohesive effect on the particulate material. It should be mentioned that a composition comprising a highly soluble compound as well as a surfactant is disclosed in EP-A-0 524 075, this composition being a liquid composition. In accordance with the present invention, it was found that the highly soluble compound having a cohesive effect on the particulate material allows to obtain a tablet having a higher elasticity at a constant compaction force or an elasticity equal to a compaction force more low comparatively with traditional tablets. Typically, a whole tablet will have an elasticity of more than 5kPa, preferably of more than 10kPa, preferably in particular for use in laundry applications, of more than 15kPa, more preferably of more than 30kPa, and most preferably of more 50 kPa, in particular for use in dishwashing or automatic dishwashing applications; and an elasticity of less than 300 kPa, preferably less than 200 kPa, preferably less than 100 kPa, more preferably less than 80 kPa, and most preferably less than 60 kPa. In fact, in case of laundry application, the tablets should be less compressed than in the case of automatic dishwashing applications, for example, where dissolution is more easily achieved, so that in a wash application of clothes, the elasticity is preferably less than 30 kPa. This allows to produce tablets having a strength and mechanical strength comparable to the strength or mechanical strength of the traditional tablets while they have a less compact tablet thus dissolving more easily. In addition, since the compound is highly soluble, the solution of the tablet is further facilitated, resulting in a synergy that leads to easier dissolution for a tablet according to the invention.

Tablet manufacturing For the purpose of manufacturing a single layer, the layer can be considered as a tablet itself. The detergent tablets of the present invention can be prepared by simply mixing the solid ingredients and compressing the mixture in a conventional tablet press as used, for example, in the pharmaceutical industry. Preferably, the main ingredients, in particular gelling surfactants, are used in the form of particles. Any liquid ingredients, for example, surfactant or foam suppressant, can be incorporated in a conventional manner into the ingredients into solid particles.

In particular for laundry tablets, the ingredients such as builder and surfactant can be spray-dried in a conventional manner and then can be compacted at a suitable pressure. Preferably, the tablets according to the invention are compressed using a force of less than 100000N, preferably less than 50000N, preferably less than 5000N and more preferably less than 3000N. In fact, the most preferred embodiment is a tablet suitable for washing compressed laundry using a force of less than 2500N, but tablets for automatic dishwashing can also be considered for example, wherein such tablets for automatic dishwashing usually They are more compressed than laundry tablets. The particulate material used to manufacture the tablet of this invention can be made by any process of particle formation or granulation. An example of such a process is spray drying (in a co-current or countercurrent spray drying tower) which typically gives low bulk densities of 600 g / L or lower. The higher density particulate materials can be prepared by granulation and densification in a batch mixer by high shear / granulator or by a continuous granulation and densification process (for example, using Lodige® CB and / or Lodige® KM mixers). ). Other suitable methods include fluidized bed processes, compacting methods (for example roll compaction), extrusion, as well as any particulate material made by any chemical method such as flocculation, crystallization, concretion, etc. The individual particles can also be any other particle, granule, sphere or grain. The components of the particulate material can be mixed together by any conventional means. The batch is suitable in, for example, a concrete mixer, Nauta mixer, ribbon mixer, or any other. Alternatively, the mixing process can be carried out continuously by measuring each component by weight in a moving band, and mixing them in one or more drum (s) or mixer (s). A non-gelling binder can be sprayed into the mixture of some or all of the components of the particulate material. Other liquid ingredients can also be sprayed into the mixture of components either separately or pre-mixed. For example, perfume and suspensions of optical brighteners can be sprayed. A finely divided flow aid (powdering agent such as zeolites, carbonates, silicas) can be added to the particulate material after spraying the binder, preferably towards the end of the process, to make the mixture less sticky. Tablets can be manufactured using any compaction process, such as tabletting, briquetting or extrusion, preferably tabletting. Suitable equipment includes a standard single-stroke press or rotary press (such as Courtoy®, Korch®, Manesty®, or Bonals®). The tablets prepared according to this invention preferably have a diameter of between 20 mm and 60 mm, preferably of at least 35 and up to 55 mm, and a weight between 25 and 100 g. The ratio of height to diameter (or width) of the tablets is preferably greater than 1: 3, more preferably greater than 1: 2. The compaction pressure used for preparing these tablets need not exceed 100000 kN / m2, preferably not exceed 30000 kN / m2, preferably not exceed 5000 kN / m2, more preferably not exceed 3000kN / m2 and most preferably not exceed 1000 kN / m2. In a preferred embodiment according to the invention, the tablet has a density of at least 0.9 g / cc, preferably at least 1.0 g / cc, and preferably less than 2.0 g / cc, more preferably less than 1.5 g / cc, more preferably less than 1.25 g / cc and most preferably less than 1.1 g / cc. Multilayer tablets are typically formed in rotary presses by placing the matrices of each layer, one after the other, in matrix force feed flasks. As the process continues, the matrix layers are then pressed into the compression and compression stage stations to form the multilayer tablet. With some rotary presses, it is also possible to compress the first feed layer before compressing the entire tablet.

Hydrotrope Compound In a preferred embodiment of the invention, a highly soluble compound having a cohesive effect is integrated into the tablet of the invention, wherein this compound is also a hydrotrope compound. Said hydrophobic compound can generally be used to promote the dissolution of the surfactant avoiding gelation, so that they can be, for example, advantageously comprised in a less elastic layer. A specific compound is defined as a hydrotrope in the following manner (see SE Friberg and M. Chiu, J. Dispersion Science and Technology, 9 (5 and 6), pages 443 to 457 (1988-1989)): 1. Prepare a solution comprising 25% by weight of the specific compound and 75% by weight of water. 2. Then octanoic acid is added to the solution in a proportion of 1.6 times the weight of the specific compound in solution, the solution being at a temperature of 20 ° Celcius. The solution is mixed in a Sotax beaker with a stirrer with a marine propeller, the impeller being positioned approximately 5 mm above the bottom of the beaker, the mixer being adjusted at a rotation speed of 200 revolutions per minute. 3. The specific compound is hydrotrope if the octanoic acid is completely solubilized, that is, if the solution comprises only one phase, the phase being a liquid phase.

It should be mentioned that in a preferred embodiment of the invention, the hydrotrope compound is a flowable material made of solid particles under operating conditions between 15 and 60 ° Celsius.

Hydrotrope compounds include the following listed compounds: A list of commercial hydrotropes could be found in McCutcheon Emulsifiers and Detergents published by the McCutcheon Division of Manufacturing Confectioners Company. Compounds of interest also include: 1. Nonionic hydrotrope with the following structure: R - O - (CH2CH2O) x (CH-CH2O) and H CH3 wherein R is a C8-C10 alkyl chain, x ranges from 1 to 15, and from 3 to 10. 2. Anionic hydrotropes such as alkali metal arylsulfonates. This includes alkali metal salts of benzoic acid, salicylic acid, benzenesulfonic acid and its many derivatives, naphthoic acid and various hydro-aromatic acids. Examples of these are sodium, potassium salts and ammonium benzenesulfonate salts derived from toluenesulfonic acid, xylenesulfonic acid, cumenesulfonic acid, tetralinsulfonic acid, naphthalenesulfonic acid, methylnaphthalenesulfonic acid, dimethylnaphthalenesulfonic acid, trimethylnaphthalenesulfonic acid.

Other examples include dialkylbenzenesulfonic acid salts such as salts of diisopropylbenzenesulfonic acid, ethylmethylbenzenesulfonic acid, alkylbenzenesulfonic acid with an alkyl chain length of 3 to 10, (preferably 4 to 9), linear or branched alkylsulfonates with an alkyl chain with 1 to 18 carbons. 3. Solvent hydrotropes such as alkoxylated glycerines and alkoxylated glycerides, alkoxylated glycerines of esters, alkoxylated fatty acids, glycerin esters, polyglycerol esters. The preferred alkoxylated glycerines have the following structure: wherein I, m, and n are each a number from 0 to about 20, with l + m + n = from about 2 to about 60, preferably from about 10 to about 45 and R represents H, CH3 or C2H5. Preferred alkoxylated glycerides have the following structure wherein R1 and R2 are each CnCOO or - (CH2CHR3-0) H where R3 = H, CH3 or C H5 and I is a number from 1 to about 60, n is a number from about 6 to about 24. 4. Polymer hydrotropes such as those described in EP636687: wherein E is a hydrophilic functional group, R is H or a C1-C10 alkyl group or is a hydrophilic functional group; R1 is H or a lower alkyl group or an aromatic group, R2 is H or a cyclic alkyl group or aromatic group. The polymer typically has a molecular weight of between about 1000 and 1000000. 5. Hydrotropes of unusual structure such as 5-carboxy-4-hexyl-2-cyclohexane-1-yl octanoic acid (Diacid®). The use of said compounds in the invention would further increase the rate of dissolution of the tablet, since a hydrotrope compound facilitates the dissolution of surfactants, for example. Such a compound could be formed from a mixture or from a single compound.

Coating The strength of the tablet according to the invention can be further improved by making a coated tablet, the coating covering an uncoated tablet according to the invention, thereby further improving the mechanical characteristics of the tablet while maintaining or improving plus the dissolution. This applies more advantageously to the multilayer tablets according to the invention, whereby the mechanical characteristics of a more elastic layer can be transmitted by coating the rest of the tablet, thereby combining the advantage of the coating with the advantage of the more elastic layer. In fact, mechanical constraints will be transmitted through the coating, thus improving the mechanical integrity of the tablet. In one embodiment of the present invention, the tablets may be coated such that the tablet does not absorb moisture, or absorb moisture only at a very slow rate. The coating is also resistant so that moderate mechanical shocks to which the tablets are subjected during handling, packing and shipping result in very low breaking or friction levels. Finally, the coating is preferably brittle so that the tablet decomposes when subjected to stronger mechanical shock. In addition, it is favorable if the coating material is dissolved under alkaline conditions, or is easily emulsified by surfactants. This helps to avoid the problem of visible residues in the window of a front loading washing machine during the washing cycle, and also avoids the deposit of undissolved particles or lumps of coating material in the laundry load. The solubility in water is measured following the test protocol of E1148-87 of ASTM entitled, "Standard test method for aqueous solubility measurements". Suitable coating materials are dicarboxylic acids. Particularly suitable dicarboxylic acids are selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, and mixtures of the same. The coating material preferably has a melting point of 40 ° C to 200 ° C. The coating can be applied in a number of ways. Two preferred coating methods are a) coating with a molten material and b) coating with a solution of the material. In a), the coating material is applied at a temperature above its melting point, and solidifies in the tablet. In b), the coating is applied as a solution, the solvent being dried to leave a consistent coating. The substantially insoluble material can be applied to the tablet by, for example, spraying or immersion.

Normally when the molten material is sprayed onto the tablet, it will solidify rapidly to form a consistent coating. When the tablets are immersed in the molten material and then removed, rapid cooling again causes rapid solidification of the coating material. Clearly substantially insoluble materials having a melting point below 40 ° C are not sufficiently solid at ambient temperatures and it has been found that materials having a melting point above about 200 ° C are not viable to be used. Preferably, the materials are melted on the scale of 60 ° C to 160 ° C, more preferably 70 ° C to 120 ° C. By "melting point" is meant the temperature at which the material to be heated slowly in, for example, a capillary tube becomes a transparent liquid. A coating of any desired thickness can be applied in accordance with the present invention. For most purposes, the coating forms from 1% to 10%, preferably from 1.5% to 5%, of the weight of the tablet. The tablet coatings of the present invention are very hard and provide extra resistance to the tablet. In a preferred embodiment of the present invention, the fracture of the coating in the wash is improved by adding a disintegrant to the coating. This disintegrant will swell once it is in contact with water and will break the coating into small pieces. This will improve the dissolution of the coating in the wash solution. The disintegrant is suspended in the molten coating at a level of up to 30%, preferably between 5% and 20%, more preferably between 5 and 10% by weight. Possible disintegrants are described in the Pharmaceutical Excipients Manual (1986). Examples of suitable disintegrants include starch: natural, modified or pregelatinized starch, sodium starch gluconate; gum: gum agar, guar gum, locust bean gum, karaya gum, pectin gum, gum tragacanth; croscarmilose-sodium, crospovidone, cellulose, carboxymethylcellulose, algenic acid and its salts including sodium alginate, silicon dioxide, clay, polyvinylpyrrolidone, soy polysaccharides, ion exchange resins, and mixtures thereof.

Resistance to stress For the purpose of measuring the tensile strength of a layer, the layer can be considered as a tablet itself. Depending on the composition of the starting material, and the shape of the tablets, the compaction force used can be adjusted so as not to affect the tensile strength, and the disintegration time in the washing machine. This method can be used to prepare homogeneous or stratified tablets of any size or shape. For a cylindrical tablet, the tensile strength corresponds to the diametral fracture stress (DFS) which is a way of expressing the strength of a tablet, and is determined by the following equation: Resistance to tension = 2F pDt where F is the maximum force (Newton) to cause voltage failure (fracture) measured by a tablet hardness tester VK 200 supplied by Van Kell Industries, Inc. D is the diameter of the tablet or layer, and t the thickness of the tablet or layer. For a non-round tablet, pD can be simply replaced by the perimeter of the tablet (see Method Pharmaceutical Dosage Forms: Tablets Volume 2 page 213 to 217). A tablet that has a diametral fracture stress less than 20 kPa is considered fragile and is likely to result in some tablets being delivered broken to the consumer. A diametral fracture stress of at least 25 kPa is preferred. This applies similarly to non-cylindrical tablets, to define the elasticity, where the normal cross section at the height of the tablet is not round, and where the force is applied along a direction perpendicular to the direction of the tablet height and normal next to the tablet, the side being perpendicular to the non-round cross section.

Supply of the tablet The delivery rate of a detergent tablet can be determined as follows: Two tablets, nominally 50 grams each, are weighed, and then placed in the dispenser of a Baucknecht® WA9850 washer. The water supply to the washing machine is adjusted to a temperature of 20 ° C and a hardness of 3.57 g / l, the inlet water flow rate of the dispenser being adjusted to 8 l / min. The level of tablet waste remaining in the dispenser is verified by changing the wash power and the wash cycle setting to wash program 4 (white / colors, short cycle). The percentage of supply residue is determined as follows:% of supply = weight of waste x 100 / weight of the original tablet The residue level is determined by repeating the procedure 10 times and an average residue level is calculated based on ten individual measurements. In this stress test, a residual of 40% of the starting tablet weight is considered acceptable. A residue of less than 30% is preferred, and less than 25% is more preferred. It is worth mentioning that the measure of water hardness is given in the traditional "grain per gallon" unit, where 0.001 mol per liter = 7.0 grains per gallon, representing the concentration of Ca2 + ions in solution.

Effervescent In another preferred embodiment of the present invention, the tablets further comprise an effervescent.

"Effervescence" as defined herein means the formation of gas bubbles from a liquid, as a result of a chemical reaction between a soluble acid source and an alkali metal carbonate, to produce gaseous carbon dioxide, ie, C6H807 + 3NaHC03? Na3C6H507 + 3CO2 t + 3H2O Additional examples of acid and carbonate sources and other effervescent systems can be found in: (Pharmaceutical Dosage Forms: Tablets Volume 1 page 287 to 291). An effervescent can be added to the tablet mix in addition to the detergent ingredients. The addition of this effervescent to the detergent tablet improves the disintegration time of the tablet. The amount will preferably be between 5 and 20% and more preferably between 10 and 20% by weight of the tablet. Preferably the effervescent should be added as an agglomerate of different particles or as a compact product, and not as separate particles. Due to the gas created by the effervescence in the tablet, the tablet may have a D.F.S. higher and still have the same disintegration time as a tablet without effervescence. When the D.F.S. of the tablet with effervescence remains the same as a tablet without effervescence, the disintegration of the tablet with effervescence will be faster. An additional dissolution aid could be provided using compounds such as sodium acetate or urea. A list of suitable dissolving aids can be found in Pharmaceutical Dosage Forms: Tablets, Volume 1, Second Edition, Edited by H.A. Lieberman et al, ISBN 0-8247-8044-2.

Detersive Surfactants The tablet according to the invention comprises surfactants. The dissolution of the surfactants is favored by the addition of the highly soluble compound. Non-limiting examples of surfactants useful herein typically at levels of about 1% to about 55%, by weight, include the conventional C 8 -C 8 alkylbenzene sulfonates ("LAS") and C 1 or C 2 0 alkyl sulfates ("AS") ) of branched chain and random, the secondary alkyl sulfates C? oC? 8 (2,3) of formula CH3 (CH2) x (CHOSO3-M +) CH3 and CH3 (CH2) and (CHOSO3-M +) CH2CH3 where xy ( and +1) are integers of at least about 7, preferably at least about 9, and M is a water-solubilizing cation, especially sodium, unsaturated sulfates such as oleyl sulfate, C10-C? 8 alkylalkoxy sulfates (" AEXS ", especially EO-1-7 ethoxysulfates), C? Or C? 8 alkylalkoxycarboxylates (especially the EO 1-5 ethoxycarboxylates), the C? 0 ~? S glycerol ethers, the C? Or C? 8 alkyl polyglycosides and their corresponding sulphated polyglycosides, and esters of alpha-sulfonated fatty acids of C? 2-C- | 8. If desired, conventional non-ionic and amphoteric surface-active agents such as C-? 2-C? 8 alkyl ethoxylates ("AE") including the so-called narrow peak alkyl ethoxylates and C6-C? 2 alkylphenol-alkoxylates (especially ethoxylates) and mixed ethoxy / propoxy), C? 2-C? 8 betaines and sulfobetaines ("sultanies"), Cio-C-is amine oxides, and the like can also be included in the general compositions. The C-io-C-is polyhydroxy fatty acid N-alkylamides can also be used. Typical examples include the N-methylglucamides of C? 2-C? S. See WO 9,206,154. Other surfactants derived from sugar include polyhydroxy fatty acid N-alkoxyamides, such as C 10 -C 8 N- (3-methoxypropyl) glucamide. The N-propyl to N-hexyl C? 2-Ci8 glucamides can be used for low foam production. Conventional C? O-C2o soaps can also be used. If high foam production is desired, branched-chain C10-C16 soaps can be used. Mixtures of anionic and nonionic surfactants are especially useful. Other conventional useful surfactants are listed in standard texts. In a preferred embodiment, the tablet comprises at least 5% by weight of surfactant, preferably at least 15% by weight, more preferably at least 25% by weight, and most preferably between 35% and 45% by weight of surfactant agent.

Non-gelling binders Non-gelling binders can be integrated into the particles forming the tablet to facilitate further dissolution. If non-gelling binders are used, suitable non-gelling binders include synthetic organic polymers such as polyethylene glycols, polyvinyl pyrrolidones, polyacrylates and water-soluble acrylate copolymers. The Pharmaceutical Excipients Second Edition manual has the following classification of binders: acacia, alginic acid, carbomer, carboxymethylcellulose-sodium, dextrin, ethylcellulose, gelatin, guar gum, hydrogenated vegetable oil type I, hydroxyethylcellulose, hydroxypropylmethylcellulose, liquid glucose, sodium silicate, magnesium-aluminum, maltodextrin, methylcellulose, polymethacrylates, povidone, sodium alginate, starch and zein. The most preferred binders also have an active cleaning function in the laundry of clothes such as cationic polymers, ie ethoxylated hexamethylenediamine quaternary compounds, bishexamethylene triamias, or others such as pentaamines, ethoxylated polyethylene amines, maleic acrylic polymers. The non-gelling binder materials are preferably sprayed and therefore have an appropriate melting point temperature below 90 ° C., preferably below 70 ° C and more preferably below 50 ° C in order not to damage or degrade the other active ingredients in the matrix. More liquid non-aqueous binders (ie, not in aqueous solution) are preferred which can be sprayed in molten form. However, they can also be solid binders incorporated in the matrix by dry addition but which have agglutination properties within the tablet. Non-gelling binder materials are preferably used in an amount within the range of 0.1 to 15% of the composition, more preferably below 5% and especially if it is an active material that is not for laundry below 2%. % by weight of the tablet. It is preferred to avoid gelling binders, such as nonionic surfactants, in their liquid form or molten form. Nonionic surfactants and other gelling binders are not excluded from the compositions, but it is preferred that they be processed into detergent tablets as components of particulate materials, and not as liquids.

Detergency builders Detergency builders may optionally be included in the compositions herein to help control mineral hardness. Inorganic as well as organic builders can be used. Builders are typically used in fabric washing compositions to aid in the removal of particulate dirt. The level of builder can vary widely depending on the final use of the composition. Inorganic or P-containing detergent builders include, but are not limited to, the alkali metal, ammonium and alkanolammonium salts of polyphosphates (exemplified by tripolyphosphates, pyrophosphates, and vitreous polymeric metaphosphates), phosphonates, phytic acid, silicates, carbonates ( including bicarbonates and sesquicarbonates), sulphates, and aluminosilicates.

However, non-phosphate builders are required in some places. Importantly, the compositions herein work surprisingly well even in the presence of so-called "weak" builders (comparatively with phosphates) such as citrate, or in the so-called "poor builder condition" which it can occur with stratified zeolite or silicate builders. Examples of silicate builders are alkali metal silicates, in particular those having an SiO2: Na2O ratio in the 1.6: 1 to 3.2: 1 scale and layered silicates, such as the layered sodium silicates described in the US Pat. US 4,664,839, issued May 12, 1987 to HP Rieck. NaSKS-6 is the brand of a crystalline layered silicate marketed by Hoechst (commonly abbreviated herein as "SKS-6"). Unlike zeolite builders, the Na SKS-6 silicate builder does not contain aluminum. NaSKS-6 has the form of a delta-Na2S05 morphology of stratified silicate. It can be prepared by methods such as those described in German DE-A-3,417,649 and DE-A-3,742,043. SKS-6 is a more preferred layered silicate for use herein, but other layered silicates, such as those having the general formula NaMSix? 2? + RyH2? Can be used herein. wherein M is sodium or hydrogen, x is a number from 1.9 to 4, preferably 2, and y is a number from 0 to 20, preferably 0. Other layered silicates from Hoechst include NaSKS-5, NaSKS-7 and NaSKS- 11, like the alpha, beta and gamma forms. As mentioned above, delta-Na2SiO5 (NaSKS-6 form) is more preferred for use herein. Other silicates may also be useful, for example, magnesium silicate, which may serve as a tightening agent in granulated formulations, as a stabilizing agent for oxygen bleaches, and as a component of foam control systems. Examples of carbonate builders are alkaline earth metal and alkali metal carbonates which are described in German Patent Application No. 2,321,001 published November 15, 1973. Aluminosilicate builders are useful in the present invention. Aluminosilicate builders are of great importance in the heavy duty granular detergent compositions marketed today, and can also be a significant detergency builder ingredient in liquid detergent formulations. The aluminosilicate builders include those that have the empirical formula: Mz (zAIO2) and] -xH2O where z and y are integers of at least 6, the molar ratio of zay is on the scale of 1.0 to about 0.5, and x is an integer from about 15 to about 264. Useful aluminosilicate ion exchange materials are commercially available. These aluminosilicates can be of crystalline or amorphous structure and can be natural aluminosilicates or derivatives in a synthetic manner. A method for producing aluminosilicate ion exchange materials is described in the U.S.A. 3 patent., 985,669, Krummel, et al, issued October 12, 1976. Preferred synthetic crystalline aluminosilicate ion exchange materials useful herein are available under the designations Zeolite A, Zeolite P (B), Zeolite MAP and Zeolite X. In an especially preferred embodiment, the crystalline aluminosilicate ion exchange material has the formula: Na 12 [(AIO 2) 2 (SiO 2) 12] -xH 2 O wherein x is from about 20 to about 30, especially about 27. This The material is known as Zeolite A. Dehydrated zeolites (x = 0-10) can also be used herein. Preferably, the aluminosilicate has a particle size of about 0.1-10 microns in diameter. Organic detergency builders suitable for the purposes of the present invention include, but are not limited to, a wide variety of polycarboxylate compounds. As used herein, "polycarboxylate" refers to compounds having a plurality of carboxylate groups, preferably at least 3 carboxylates. The polycarboxylate builder in general can be added to the composition in acid form, but can also be added in the form of a neutralized salt. When used in salt form, alkali metal salts, such as sodium, potassium, and lithium, or alkanolammonium salts, are preferred.

Polycarboxylate detergent builders include a variety of categories of useful materials. An important category of polycarboxylate builders includes the ether polycarboxylates, including oxydisuccinate, as described in Berg, US Patent 3,128,287, issued April 7, 1964, and Lamberti et al, US Patent 3,635,830, issued 18 January 1972. See also detergent builders "TMS / TDS" of US Patent 4,663,071, issued to Bush et al, May 5, 1987. Suitable ether polycarboxylates also include cyclic compounds, particularly alicyclic compounds, such as those they are described in US Patents 3,923,679; 3,835,163; 4,158,635; 4,120,874 and 4,102,903. Other useful detergency builders include the ether hydroxypolycarboxylates, maleic anhydride copolymers with ethylene or vinyl methyl ether, 1,3,5-trihydroxybenzene-2,4,6-trisulfonic acid, and carboxymethyloxysuccinic acid, the different alkali metal salts, ammonium, and substituted ammonium salts of polyacetic acids such as ethyl ndiaminotetraacetic acid and nitrilotriacetic acid as well as polycarboxylates such as mellitic acid, succinic acid, oxydisuccinic acid, polymaleic acid, benzene-1, 3,5-tricarboxylic acid, carboxymethyloxysuccinic acid, and soluble salts of the same. Citrate detergency builders, for example, citric acid, and soluble salts thereof (in particular sodium salt), are polycarboxylate builders of particular importance for formulations. liquid detergents for heavy work due to its availability of renewable resources and its biodegradability. The citrates can also be used in granular compositions, especially in combination with layered zeolite and / or silicate builders. Oxydisuccinates are also especially useful in said compositions and combinations. Also suitable in the detergent compositions of the present invention are 3,3-dicarboxy-4-oxa-1,6-hexanedioates and the related compounds described in the U.S.A. No. 4,566,984, Bush, issued January 28, 1986. Useful succinic acid builders include alkylsuccinic and alkenyl succinic acids of C5-C2o, and salts thereof. A particularly preferred compound of this type is dodecenylsuccinic acid. Specific examples of succinate builders include: laurylsuccinate, myristylsuccinate, palmitylsuccinate, 2-dodecenylsuccinate (preferred), 2-pentadecenylsuccinate, and the like. Lauryl succinates are the preferred builders of this group, and are described in European patent application 86200690.5 / 0,200,263, published on November 5, 1986. Other suitable polycarboxylates are described in US Pat. 4,144,226, Crutchfield et al., Issued March 13, 1979 and in the U.S. patent. 3,308,067, Diehl, issued March 7, 1967. See also Diehl patent of E.U.A. 3,723,322. Fatty acids, for example, C 2 -C 8 monocarboxylic acids, can also be incorporated into the compositions alone, or in combination with the aforementioned builders, especially citrate and / or succinate builders, for provide additional detergency builder activity. Said use of fatty acids will generally result in a decrease in foam production, which can be taken into account by the formulator. In situations where phosphorus-based detergency builders can be used, and especially the formulation of bars used for manual washing operations, the various alkali metal phosphates such as the well-known sodium tripolyphosphates, sodium pyrophosphate and the like can be used. sodium orthophosphate. Phosphonate detergency builders such as ethane-1-hydroxy-1,1-bisphosphonate and other known phosphonates (see, for example, U.S. Patents 3,159,581, 3,213,030, 3,422,021, 3,400,148 and 3,422,137) can also be used.

Bleach The detergent compositions herein may optionally contain bleaching agents or bleaching compositions containing a bleaching agent and one or more bleach activators. When present, bleaching agents will typically be at levels of from about 1% to about 30%, more typically from about 5% to about 20%, of the detergent composition, especially for fabric washing. If present, the amount of bleach activators will typically be from about 0.1% to about 60%, more typically from about 0.5% to about 40% of the bleaching composition comprising the bleach-plus-bleach activating agent. The bleaching agents used herein may be any of the bleaching agents useful for detergent compositions in textile cleaning, hard surface cleaning, or other cleaning purposes that are known or are now disclosed. These include oxygen bleaches as well as other bleaching agents. Perborate whiteners, for example, sodium perborate (eg, mono- or tetrahydrate) can be used herein. Another category of bleaching agent that can be used without restriction includes percarboxylic acid bleaching agents, and salts thereof. Suitable examples of this class of agent include magnesium monoperoxyphthalate hexahydrate, the magnesium salt of metachlorophenobenzoic acid, 4-non-lamino-4-oxoperoxybutyric acid and diperoxydecanedioic acid. Said bleaching agents are described in the patent of E.U.A. 4,483,781, Hartman, issued November 20, 1984, patent application of E.U.A. 740,446, Burns et al., Filed June 3, 1985, European patent application 0,133,354, Banks et al., Published February 20, 1985, and patent of E.U.A. 4,412,934, Chung et al., Issued November 1, 1983. More preferred bleaching agents also include 6-nonylamino-6-oxoperoxycaproic acid as described in the U.S. patent. 4,634,551, issued on January 6, 1987 to Burns et al.

Peroxygen bleach agents can also be used. Suitable peroxygen bleach compounds include sodium carbonate peroxyhydrate and equivalent "percarbonate" bleaches, sodium pyrophosphate peroxyhydrate, urea peroxyhydrate, and sodium peroxide. Persulfate bleach can also be used (for example, OXONE, manufactured commercially by DuPont). A preferred percarbonate bleach comprises dry particles having an average particle size in the range of about 500 microns to about 1,000 microns, no more than about 10% by weight of said particles being less than about 200 microns and not more than about 200 microns. about 10% by weight of said particles being greater than about 1.250 microns. Optionally, the percarbonate can be coated with silicate, borate or water soluble surfactants. Percarbonate is available from several commercial sources such as FMC, Sovay and Tokai Denka. Mixtures of bleaching agents can also be used. Peroxygen bleaching agents, perborates, percarbonates, etc., are preferably combined with bleach activators, which leads to in situ production in aqueous solution (ie, during the washing process) of the peroxyacid corresponding to the activator bleaching. Several non-limiting examples of activators are described in the patent of E.U.A. 4,915,854, issued April 10, 1990 to Mao et al., And the US patent. 4,412,934. The activators of nonanoyloxybenzenesulfonate (NOBS) and tetraacetylethylenediamine (TAED) are typical, and mixtures thereof can also be used. See also patent of E.U.A. 4,634,551 for other typical bleaches and activators useful herein. More preferred amido derivative whitening activators are those of the formulas: R 1 N (R 5) C (O) R 2 C (O) L or R 1 C (O) N (R 5) R 2 C (O) L wherein R 1 is an alkyl group containing from about 6 to about 12 carbon atoms, R 2 is an alkylene containing from 1 to about 6 carbon atoms, R 5 is H or alkyl, aryl, or alkaryl containing from about 1 to about 10 carbon atoms, and L is any suitable leaving group. A leaving group is any group that is displaced from the bleach activator as a result of the nucleophilic attack in the bleach activator by the perhydrolysis anion. A preferred leaving group is phenylsulfonate. Preferred examples of bleach activators of the above formulas include (6-ochatanamido-caproyl) oxybenzenesulfonate, (6-nonanamidocaproyl) oxybenzenesulfonate, (6-decanamido-caproyl) oxybenzenesulfonate, and mixtures thereof, as described in the patent from the USA 4,634,551, which is incorporated herein by reference. Another class of bleach activators comprises the benzoxaine activators described by Hodge et al., In the U.S. patent. 4,966,723, issued October 30, 1990, which is incorporated herein by reference. A more preferred benzoxaine type activator is: Another class of preferred bleach activators includes acyl-lactam activators, especially acylcaprolactams and acylvalerolactams of the formulas: wherein R6 is H or an alkyl, aryl, alkoxyaryl, or alkaryl group containing 1 to about 12 carbon atoms. More preferred lactam activators include benzoylcaprolactam, octanoylcaprolactam, 3,5,5-trimethylhexanoylcaprolactam, nonanoylcaprolactam, decanoylcaprolactam, undecenoylcaprolactam, benzoylvalerolactam, octanoylvalerolactam, decanoylvalerolactam, undecenoylvalerolactam, nonanoylvalerolactam, 3,5,5-trimethylhexanoylvalerolactam, and mixtures thereof. See also patent of E.U.A. No. 4,545,784, issued to Sanderson, October 8, 1985, which is incorporated herein by reference, which discloses acylcaprolactams, including benzoylcaprolactam, adsorbed on sodium perborate. Bleaching agents other than oxygen bleaching agents are also known in the art and can be used herein. One type of non-oxygen bleaching agent of particular interest includes photoactivated bleaching agents such as sulfonated zinc and / or aluminum phthalocyanines. See patent of E.U.A. 4,033,718, issued July 5, 1977 to Holcombe et al. If used, the detergent compositions will typically contain from about 0.025% to about 1.25% by weight of said bleaches, especially sulfonated zinc phthalocyanine. If desired, the bleaching compounds can be catalyzed by a manganese compound. Such compounds are well known in the art and include, for example, the manganese-based catalysts described in the U.S.A. 5,246,621, patent of E.U.A. 5,244,594; patent of E.U.A. 5,194,416; patent of E.U.A. 5,114,606; and European Patent Application Publication Nos. 549,271 A1, 549,272A1, 544,440A2 and 544,490A1. Preferred examples of these catalysts include Mn,? 'V 2 (uO) 3 (1, 4,7-trimethyl-1, 4,7-triazacyclononane) 2 (PF6) 2) Mnlll2 (u-0) 1 (u-OAc) 2 (1 , 4,7-trimethyl-1, 4,7-triazacyclononane) 2- (CI04) 2; Mn j'vv4 (uO) 6 (1, 4,7-triazacyclononane) 4 (CIO4) 4, Mn '"Mnlv4 (uO)? (U-OAc) 2- (1, 4,7-trimeti, 4.7 -triazaciclonane) 2 (CIO) 3, Mn? v (1, 4,7-trimethyl-1, 4,7-triazacyclononane) - (OCH 3) 3 (PF 6), and mixtures thereof. of metal include those described in US Patent 4,430,243 and US Patent 5,114,611 The use of manganese with various complex ligands to improve bleaching is also reported in the following US Patents 4,728,455, 5,284,944, 5,246,612, 5,256,770, 5,280,117, 5,274,147 5,153,161 and 5,227,084 As a practical matter, and not by way of limitation, the compositions and methods herein can be adjusted to provide in the order of at least one part per ten million active bleaching catalyst species. in the aqueous wash solution, and preferably will provide from about 0.1 ppm to about 700 ppm, more preferably from about 1 ppm to about and 500 ppm, of the catalyst species in the wash solution.

Enzymes Enzymes may be included in the formulations herein for a wide variety of fabric washing purposes, including removal of protein-based, carbohydrate-based, or triglyceride-based stains, for example, and to avoid dye transfer migratory, and for fabric restoration. Enzymes to be incorporated include proteases, amylases, lipases, cellulases, and peroxidases, as well as mixtures thereof. Other types of enzymes can also be included. They can be of any suitable origin, such as vegetable, animal, bacterial, fungal and yeast. However, its choice is governed by several factors such as pH activity and / or optimum stability, thermostability, stability against active detergents, builders, etc. In this regard, bacterial or fungal enzymes, such as bacterial amylases and proteases, and fungal cellulases, are preferred. Enzymes are normally incorporated at levels sufficient to provide up to about 5 mg by weight, more typically about 0.01 mg to about 3 mg, of active enzyme per gram of the composition. In other words, the compositions herein will typically contain from about 0.001% to about 5%, preferably 0.01% -1% by weight of a commercial enzyme preparation. Protease enzymes are usually present in such commercial preparations at levels sufficient to provide 0.005 to 0.1 Anson units (AU) of activity per gram of composition. Suitable examples of proteases are subtilisins which are obtained from particular strains of B. subtilis and B. licheniformis. Another suitable protease is obtained from a strain of Bacillus, which has a maximum activity in the pH range of 8-12, developed and sold by Novo Industries A / S, under the registered trade name ESPERASE. The preparation of this enzyme and analogous enzymes is described in British patent specification No. 1, 243,784 by Novo. Suitable proteolytic enzymes for removing stains based on proteins that are commercially available include those sold under the tradenames ALCALASE and SAVINASE by Novo Industries A / S (Denmark) and MAXATASE by International Bio-Synthetics, Inc. (The Netherlands). Other proteases include Protease A (see European Patent Application 130,756, published January 9, 1985) and Protease B (see European Patent Application Serial No. 87303761.8, filed April 28, 1987, and European Patent Application 130,756 , Bott et al, published on January 9, 1985). Amylases include, for example, α-amylases described in British Patent Specification No. 1, 296,839 (Novo), RAPIDASE, International Bio-Synthetics, Inc. and TERMAMYL, Novo Industries. The cellulases that can be used in the present invention include both bacterial and fungal cellulose. Preferably, they will have an optimum pH between 5 and 9.5. Suitable cellulases are described in the US patent. 4,435,307, Barbesgoard et al, issued March 6, 1984, which describes fungal cellulases produced from Humicola insolens and the DSM 1800 strain of Humicola or a fungus that produces the cellulase 212 belonging to the genus Aeromonas, and cellulases extracted from the hepatopancreas of marine mollusk Dolabella auricula Solander. Suitable cellulases are also described in GB-A-2,075,028; GB-A-2,095,275 and DE-OS-2,247,832. CAREZYME (Novo) is especially useful. Suitable lipase enzymes for detergent use include those produced by microorganisms of the Pseudomonas group, such as Pseudomonas stutzeri ATCC 19,154, as described in British Patent 1, 372,034. See also lipases in Japanese patent application 53,20487, open to public inspection on February 24, 1978. This lipase is available from Amano Pharmaceutical Co. Ltd., Nagoya, Japan, under the trade name Lipase P "Amano", that in the future will be called "Amano-P". Other commercial lipases include Amano-CES, lipases ex Choromobacter viscosum, e.g., Chromobacter viscosum var. lipolyticum NRRLB 3673, commercially available from Toyo Jozo Co., Tagata, Japan; and other lipases from Chromobacter viscosum, from U.S. Biochemical Corp., E.U.A. and Disoynth Co., The Netherlands, and lipases ex Pseudomonas gladioli. The LIPOLASE enzyme derived from Humicola lanuginosa and commercially available from Novo (see also EPO 341, 947), is a preferred lipase for use herein. Peroxidase enzymes are used in combination with oxygen sources, for example, percarbonate, perborate, persulfate, hydrogen peroxide, etc. They are used for "bleaching in solution" that is, to avoid transfer of dyes or pigments removed from substrates during washing operations to other substrates in the washing solution. Peroxidase enzymes are known in the art and include, for example, horseradish peroxidase, ligninase, and haloperoxidase such as chloro- and bromo-peroxidase. Peroxidase-containing detergent compositions are described, for example, in PCT International Application WO 89/099813, published October 19, 1989, by O. Kirk, assigned to Novo Industries A / S.

A wide range of enzyme materials and means for their incorporation into synthetic detergent compositions are also described in U.S. Patent 3,553,139, issued January 5, 1971 to McCarty et al. In the patent of E.U.A. 4,101, 457, Place et al, issued July 18, 1978, and in the patent of E.U.A. 4,507,219, Hughes, issued March 26, 1985 also describes enzymes. Useful enzyme materials for liquid detergent formulations, and their incorporation into such formulations, are described in the US patent. 4,261, 868, Hora et al, issued April 14, 1981. Enzymes for use in detergents can be stabilized by various techniques. Enzyme stabilization techniques are described and exemplified in the US patent. 3,600,319, issued August 17, 1971, to Gedge, et al, and European patent application publication No. 0 199 405, application No. 86200586.5, published October 29, 1986, Venegas. Enzyme stabilization systems are also described, for example, in the U.S. patent. 3,519,570. Other components that are commonly used in detergent compositions and that can be incorporated into the detergent tablets of the present invention include chelating agents, soil removal agents, soil anti-redeposition agents, dispersing agents, brighteners, suds suppressors, fabric softeners, agents for inhibiting the transfer of dyes and perfumes.

Washing method It is known to place traditional laundry detergent tablets in the wash tub together with laundry. However, this method tends to result in unpleasant-looking residues that appear visibly in the window, especially in certain types of washing machines that have been designed to operate with low water consumption. In extreme cases, visible residues may also be left on clothes at the end of the wash cycle due to incomplete dissolution. The tablet according to the invention can be used in accordance with a washing method which significantly avoids this problem. The new method comprises preparing an aqueous solution of a laundry detergent for use in a washing machine, wherein the aqueous laundry detergent solution is formed by dissolving in water a tablet according to the invention. A preferred method relates more specifically to the preparation of an aqueous solution of a laundry detergent for use in a front loading washing machine, the front loading washing machine having a supply compartment and a washing tub, wherein the solution Aqueous detergent for washing clothes is formed by dissolving a detergent tablet in water, characterized in that the detergent tablet is placed in the supply compartment and water is passed through the supply compartment so that the tablet is supplied as a solution of a detergent for washing clothes, the aqueous solution being passed afterwards in the washing tub.

EXAMPLES EXAMPLE 1 i) A detergent base powder of composition C was prepared in the following manner (see following table): all the particulate material of the base composition was mixed in a mixing tub or spray tub to form a homogeneous particulate mixture. During this mixing, the binder system was sprayed. After this step, the matrix was separated into two different samples. The sticky hydrotop DIBS was added to only one of the samples, and then processed independently in a Loedige KM 600®. The DIBS layer was used for a more elastic lower layer, and the non-DIBS layer was used for a less elastic upper layer of a double layer tablet. ii) Using a Bonals® rotary press, both matrices were filled into two separate force feeding flasks. The matrix with DIBS is filled consecutively first in the turret stations, followed by the second matrix (the matrix without DIBS). Both layers are compressed in the pre-compression and compression stations to form a double-layer tablet with a more elastic lower layer. iii) In this particular example, the tablets have a rectangular cross section of 62.5 by 38.5 mm, a height of 20.5 mm and a weight of 48 g. The height of the lower layer corresponded to 25% of the total height of the tablet. If a round tablet is obtained from a matrix of the lower layer with the same density as in the rectangular tablet (983 g / l), the elasticity of the layer is 7.8 kPa. Using the same experiment (for a density of 991 g / l), the top layer of the tablet has an equivalent elasticity of 5.1 kPa. The elasticity measurements gave values of 1.8 J / kN for the upper layer, and 3.3 J / kN for the lower layer. iv) To have a reference for the tests, the tablets were obtained by running the press with the same press values but using the matrix without DIBS for both layers. This tablet has exactly the same density (991 g / l) and strength as the upper layer of the double layer tablets. The only difference between the double-layer tablet and the reference tablet is that the double layer tablet has a lower layer made of the matrix having DIBS in its composition. v) To test the fact that a stronger lower layer improves resistance in the line, double-layer and reference tablets were conducted through a series of line roller belts, and then analyzed separately for grades of breaking. More than one hundred tablets from each series were obtained and analyzed for the tests. vi) To prove that the supply properties are not affected by the more elastic lower layer, 10 tablets of each type were tested with the standard supply tests described above. vii) A difference was found between the double layer tablets and the reference tablets. Most of the reference tablets suffered severe damage to the lower layer (the part of the tablets in contact with the roller belts and the belts in general), while the double layer tablets with a more elastic lower layer almost did not suffer damage. A clear difference in the amount of fractionated tablets was also significantly reduced. The supply properties of the double-layer tablet were not affected by the more elastic lower layer. The following table summarizes the results of the tests carried out.

Below are examples for a composition of base particulate material for obtaining laundry detergent tablets according to the invention, whereby a more elastic layer can be more compressed than a less elastic layer, or by means of which they can be used or adapt different compositions for each layer.

The anionic agglomerates 1 comprise 40% anionic surfactant, 27% zeolite and 33% carbonate. The anionic agglomerates 2 comprise 40% anionic surfactant, 28% zeolite and 32% carbonate. The cationic agglomerates comprise 20% cationic surfactant, 56% zeolite and 24% sulfate.

The layered silicate comprises 95% SKS 6 and 5% silicate. The bleach activator agglomerates comprise 81% TAED, 17% acrylic / maleic copolymer (acid form) and 2% water. The sodium salt particle of ethylenediamine-N, N-disuccinic acid / sulfate comprises 58% sodium salt of ethylenediamine-N, N-disuccinic acid, 23% sulfate and 19% water. Sulfonated zinc phthalocyanine encapsulates are 10% active. The foam suppressor comprises 11.5% silicone oil (ex Dow Corning); 59% zeolite and 29.5% water. The binder sprinkler system comprises 50% Lutensit K-HD 96 and 50% PEG (polyethylene glycol).

The anionic agglomerates 1 comprise 40% anionic surfactant, 27% zeolite and 33% carbonate. The anionic agglomerates 2 comprise 40% anionic surfactant, 28% zeolite and 32% carbonate. The cationic agglomerates comprise 20% cationic surfactant, 56% zeolite and 24% sulfate. The layered silicate comprises 95% SKS 6 and 5% silicate. The bleach activator agglomerates comprise 81% of TAED, 17% acrylic / maleic copolymer (acid form) and 2% water.

The sodium salt particle of ethylenediamine-N, N-disuccinic acid / sulfate comprises 58% sodium salt of ethylenediamine-N, N-disuccinic acid, 23% sulfate and 19% water. Sulfonated zinc phthalocyanine encapsulates are 10% active. The foam suppressor comprises 11.5% silicone oil (ex Dow Corning); 59% zeolite and 29.5% water. The binder sprinkler system comprises 50% Lutensit K-HD 96 and 50% PEG (polyethylene glycol).

The anionic agglomerates 1 comprise 40% anionic surfactant, 27% zeolite and 33% carbonate. The anionic agglomerates 2 comprise 40% anionic surfactant, 28% zeolite and 32% carbonate. The nonionic agglomerates comprise 26% nonionic surfactant, 6% Lutensit K-HD 96, 40% anhydrous sodium acetate, 20% carbonate and 8% zeolite. The cationic agglomerates comprise 20% cationic surfactant, 56% zeolite and 24% sulfate. The layered silicate comprises 95% SKS 6 and 5% silicate. The bleach activator agglomerates comprise 81% TAED, 17% acrylic / maleic copolymer (acid form) and 2% water. The sodium salt particle of ethylenediamine-N, N-disuccinic acid / sulfate comprises 58% sodium salt of ethylenediamine-N, N-disuccinic acid, 23% sulfate and 19% water. Sulfonated zinc phthalocyanine encapsulates are 10% active. The foam suppressor comprises 11.5% silicone oil (ex Dow Corning); 59% zeolite and 29.5% water. * The binder sprinkler system comprises 0.5 parts of Lutensit K-HD 96 and 2.5 parts of PEG.

The anionic agglomerates 1 comprise 40% anionic surfactant, 27% zeolite and 33% carbonate. The cationic agglomerates comprise 20% cationic surfactant, 56% zeolite and 24% sulfate. The layered silicate comprises 95% SKS 6 and 5% silicate.

The bleach activator agglomerates comprise 81% TAED, 17% acrylic / maleic copolymer (acid form) and 2% water. The sodium salt particle of ethylenediamine-N, N-disuccinic acid / sulfate comprises 58% sodium salt of etiiendiamine- N, N-disuccinic acid, 23% sulfate and 19% water.

"• Sulfonated zinc phthalocyanine encapsulates are 10% active.The foam suppressor comprises 11.5% silicone oil (ex Dow Corning), 59% zeolite and 29.5% water.10 Perfume packages comprise 50% perfume and 50% starch The polymer particle comprises 36%, 54% zeolite and 10% water.The nonionic spray system comprises 67% C12-C15 AE5 (alcohol with an average of 5 ethoxy groups per molecule), 24% N-methylglucosamide and 9% water.

Claims (10)

NOVELTY OF THE INVENTION CLAIMS

1. A detergent tablet having at least one first and second layer, characterized in that the first layer is less elastic ^ < ? that the second layer, and if said tablet has more than two layers, the tablet is such that a less elastic layer is located at one end of the tablet.

2. The tablet according to claim 1, further characterized in that the tablet composition comprises sodium diisoalkylbenzenesulfonate.

3. The tablet according to claim 1, further characterized in that the less elastic layer comprises higher levels by weight of surfactants.

4. The tablet according to claim 1, further characterized in that the tablet is such that the less elastic layer is located at one end of the tablet.

5. The tablet according to claim 1, further characterized in that the tablet is such that the most elastic layer is located at one end of the tablet.

6. The tablet according to claim 1, further characterized in that the whole tablet contains at least 5% by weight of surfactant.

7 -. 7 - The tablet according to claim 1, further characterized in that the entire tablet has a density of at least 0.9 g / cc, preferably less than 2 g / cc.

8. The tablet according to claim 1, further characterized in that the tablet has a substantially square or rectangular cross section.

9. A coated tablet, characterized in that the uncoated tablet is in accordance with any of the preceding claims.

10. A method for manufacturing a tablet according to the invention, characterized in that the more elastic layer of the tablet is placed on the lower end of the tablet during its production.