CN1322240A - 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

Multi-layer tablet detergent with different elasticity

The present invention relates to detergent tablets, in particular those suitable for laundry.

Although detergents in tablet form are often proposed, and although products in unit dose (unitdispensing) form have many advantages, such compositions have not achieved substantial success (other than soap bars for personal washing products). One reason for this is that tablets typically dissolve more slowly than the powder of ingredients from which they are made, simply because the powder of ingredients are tightly packed together in the tablet, in contrast to allowing less opportunity for water to penetrate into between them. This leads to problems with residues resulting from slow dissolution of the detergent tablet, such as the residues being visible through the door of the washing machine during the wash cycle, or sticking to the fabric after the wash cycle is over, or both. This can be compensated by using low compression forces to maintain high porosity and good dissolution profile. However, such tablets are generally softer and have mechanical properties that are prone to breakage during manufacture or handling.

In DE-a-2207633, published on 30.8.1973, a tablet is disclosed having three layers, a middle layer sandwiched between two outer layers, which are prepared to protect the middle layer from mechanical shock while allowing the tablet to dissolve in less than 1 minute.

However, the problem of residues of detergent tablets being visible in the window of the washing machine is still encountered, in particular in certain front-loading washing machines. In fact, the dissolution problems appear particularly acute, especially for detergent tablets, due to e.g. the tendency of the surfactant to gel, or due to the use of smaller amounts of water for environmental protection or due to dissolution at low temperatures, etc.

It is an object of the present invention to provide tablets, generally formed by compressing particulate material, which are suitable for storage, transport and handling, do not break down and dissolve easily and quickly in the wash solution, release the active ingredient into the wash liquor and decompose and disperse completely in alkaline or surfactant-rich solutions (e.g., wash liquors).

Summary 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 the tablet has more than two layers, the tablet has a less elastic layer at its ends.

Detailed description of the invention

FIG. 1 represents two typical curves for measuring the elasticity of a layer or sheet, which curves represent the load applied to the sheet or layer (corresponding to the resistance of the sheet or layer) as a function of the displacement of the load along the major axis of the sheet or layer. Curves corresponding to more elastic and less elastic sheets or layers are also shown, while illustrating the structural changes experienced in the corresponding sheet or layer during the measurement.

Figure 2 represents a typical curve for measuring the elasticity of a layer or sheet, said curve representing the load applied to said sheet or layer (corresponding to the resistance of said sheet or layer) as a function of the displacement of said load along the major axis of said sheet or layer. The breaking point assigned to the highest value H of the curve and the area a below the curve from the breaking point are recorded, wherein the elasticity is derived from a divided by H.

The present invention relates to a detergent tablet. The term "detergent" means that the detergent tablet contains a surfactant. A "sheet" is defined as having a height along a major axis and a cross-section perpendicular to the major axis that preferably remains substantially constant when moving along the major axis, the sheet having two ends, one at each end of the major axis and having a surface area substantially equal to the cross-section of the sheet.

The tablet includes at least a first layer and a second layer. Typically these layers are prepared by compressing a particulate material. The composition of the layers may be the same or different, and the compressive forces used to form the layers may also be the same or different. It should be noted that the preferred embodiment of the tablet according to the invention comprises only two layers, but tablets comprising more layers are also contemplated.

According to the invention, a layer, preferably as part of a tablet, is prepared by compressing a particulate material, this part of the tablet having a height along its major axis and a cross-section corresponding to the cross-section of the tablet, such that the composition or physical and mechanical properties of this part are different from the rest of the tablet. In other words, the detergent tablet according to the present invention is formed by stacking a plurality of layers along the major axis, and the layers are mechanically or chemically bonded to each other. After separation, each layer may be considered a single layer of detergent tablet, for example, in terms of composition.

According to the invention, the first layer is less elastic than the second layer. The term "lower elasticity" is to be understood as having an elasticity which is lower than the elasticity of the second layer. When more than two layers are present in the tablet, the less elastic layer is understood simply to mean that there is another layer of higher elasticity in the tablet. In other words, if there are three layers with different and gradually changing elasticity, there are two layers of lower elasticity. According to the invention, the lowest elastic layer is the most brittle layer of all the layers of the sheet. For the purposes of the present invention, brittle is understood to be opposed to elastic. The same is true for the more elastic (i.e., less brittle), or the most elastic (i.e., least brittle). Typically the lower elastic layer has an elasticity which is 10% lower, preferably 20% lower, more preferably 30% lower, even more preferably 40% lower and most preferably 50% lower than the elasticity of the portion of the higher elastic layer in the same sheet. According to the invention, the elastic-brittle range is determined by the elasticity E of the sheet.

According to the present invention, if the detergent tablet has more than two layers, the detergent tablet has a lower elasticity layer at its end. The lower elastic layer need not be the lowest elastic layer. In a preferred embodiment, the lowest elastic layer is located on one end. The lower elastic layer is exposed at the ends so that it is more surface active and thus facilitates dissolution. Indeed, according to the present invention, the mechanical and dissolution properties of the individual sheets may be more independent of each other, so that the higher elastic layer will more specifically provide mechanical integrity and protection, while the lower elastic layer will more specifically facilitate rapid and efficient dissolution. In fact, the less elastic layer (and thus also the more brittle layer) will be readily dispersed in the solution.

Different parameters (e.g., different chemical compositions or different compressive forces) may be used to set the level of elasticity of the different layers. In particular, if a different composition is used, one layer may include more binder than another layer used to make a layer of higher elasticity (i.e., less brittle). It will be appreciated that it is preferred to have a higher level of surfactant per unit weight of the less elastic layer. In fact, the less elastic layer will be more soluble and will therefore compensate for the gelling of the surfactant by its brittleness. Indeed, gelation of the surfactant prevents rapid and efficient dissolution, which can be compensated by such surfactant concentrated on the lower elastic layer. The combination of a high solubility compound, a hydrotrope compound, and a compound that provides a high adhesion effect at lower compressive forces is advantageous for this compensation.

In another preferred embodiment and in the two-layer tablet of the present invention, the more elastic layer of the tablet is located on the end of the tablet. In fact, we have found that a less brittle layer on one end of the tablet is sufficient to obtain good mechanical properties. This is particularly suitable for the process of making the tablet of the present invention wherein the less brittle (i.e. more elastic) layer of the tablet is placed at the bottom end of the tablet during manufacture. Even more preferably the least brittle (i.e. most elastic) layer is placed at the bottom end of the sheet during production. In fact, the mechanical stresses during production are particularly high, at which stage almost only the bottom end of the sheet is mechanically stressed. Furthermore, this makes it possible to place a more brittle layer on the other end of the tablet while obtaining good mechanical resistance, wherein the more brittle layer is advantageous for providing a more active surface in contact with the solution when dissolving the detergent tablet in the solution.

We have found that this mechanical resistance can be improved when using sheets having a substantially rectangular cross-section. In fact, the stiffness of the sheet can be improved at a constant compression value by using a rectangular sheet. Rectangular sheets have much higher mechanical resistance than circular sheets at equal weight, equal compression force, equal composition, equal height, and equal volume. This applies in particular to square sheets.

Preferably one layer has a height of 5 to 95% of the overall sheet height. More preferably, the more elastic the layer, the thinner it is to minimize the effect on complete dissolution of the entire sheet.

In a preferred embodiment, the tablet according to the invention will comprise layers of different hardness (or softness) wherein their tensile strength will also be different, preferably the tablet will comprise a softer layer having a tensile strength of 5-100kPa and a harder layer having a tensile strength of 5.5 to 150 kPa. In a preferred embodiment according to the invention, the tablet comprises at least two layers of different hardness, the higher hardness layer being more resistant to mechanical shocks and the softer layer having better dissolution properties. In the most preferred embodiment according to the invention, the more brittle layer is also the softer layer and the more elastic layer is also harder. However, this may not be the case. Elasticity

The elasticity of the tablets or layers in the tablets was evaluated as follows: 1-pressing a weight flat against one end of the sheet or layer to be tested for elasticity, said weight being pressed down in the direction of the major axis of said sheet or layer. 2-measuring the force exerted by the weight as a function of its displacement. 3-two possible curves were obtained by this method as illustrated in FIG. 1. These two curves show the curves obtained for two different types of sheets or layers, one of which is more elastic than the other, which in turn is more brittle (i.e. less elastic). From this experimental curve, the elasticity value of the corresponding test piece or layer is calculated as follows:

the area below the curve and after the break point is calculated by integrating the curve (from its highest value to its maximum displacement value). This area a is then divided by the height H of the curve at the breaking point to give the elasticity E of the sheet or layer. This is illustrated in fig. 2. Higher values of E indicate higher elasticity, while lower values indicate a highly brittle layer or sheet.

To perform the experiment, the following equipment was used: an Instron4444 series mechanical tester with a standard load cell of 2KN connected to a conventional PC computer. The program for the calculation was series ix (version 7.49.00, supplied by the supplier of the equipment). Crush the sheet or layer using a Plexiglas cylinder of 25mm diameter, 30mm height and 18g weight. A standard mould (dye) for the preparation of sheets or layers, said mould having a diameter of 54 mm. Place the sheet or layer on the plate of the Instron4444 and the Plexiglas cylinder in the middle of the end of the sheet or layer. Moving the crosshead of the load cell at a constant speed of 10mm/min and the computer starting to record the resistance generated by the sheet with respect to the displacement of the cylinder into the sheet. The elasticity is calculated by dividing the area under the curve after the breaking point by its maximum height (cf. the figures and explanations above). The units of elasticity measured here are J/kN (units of area are joules and of the maximum height are kN, used to normalize the area curve).

In general, preferred embodiments for the detergent tablets according to the invention and more particularly suitable for laundry use have an elasticity value of from 0.5 to 5J/kN, more preferably from 1 to 4J/kN. For laundry applications, a more elastic layer or sheet is preferred, for example having an elasticity of from 3 to 4J/kN, more preferably from 3.1 to 3.5J/kN. More brittle layers or tablets are preferred for laundry applications, e.g. having an elasticity of 1.5 to 2.5J/kN, more preferably 1.7 to 2.1J/kN. Highly soluble compounds

In a preferred embodiment, it is preferred that the tablet contains a highly soluble compound. More preferably, higher levels of such compounds per unit weight are contained or present in the more elastic layer (i.e. the less brittle layer) of the tablet to facilitate dissolution. In fact, it is preferred that the compound assists in the dissolution of the higher elastic layer, since for example the layer is more compressed than the brittle layer. Such compounds may be formed from mixtures or from individual compounds. Highly soluble compounds are defined as follows:

solutions were prepared from deionized water and 20g/L of the specified compound as follows: 1-20 g of the specified compound were placed in a Sotax beaker. The beaker was placed in a thermostatic bath set at 10 ℃. A stirrer with a marine propeller was placed in the beaker such that the paddle of the stirrer was 5mm above the bottom of the Sotax beaker. The rotation rate of the mixer was set at 200 revolutions per minute. 2-980 g of deionized water were introduced into the Sotax beaker. 3-after 10s of introduction of the water, the conductivity of the solution was measured using a conductivity meter. 4-repeat step 3 at 20, 30, 40, 50, 1 minute, 2 minutes, 5 minutes and 10 minutes after step 2. The measurement values from 5 to 10 minutes were used as plateau or maximum values.

According to the invention, the specific compound is highly soluble when the conductivity of the solution reaches 80% of its maximum value within 10 seconds after complete addition of deionized water to the compound. In fact, when the conductivity is monitored in this way, it reaches a plateau value after a period of time, which is considered to be the maximum value. Preferably, such compounds are in a form flowable at between 10 and 80 ℃ comprised of solid particles for ease of handling, but other forms such as slurries or liquids may be used.

Examples of the highly soluble compound include sodium diisoalkylbenzene sulfonate or sodium toluene sulfonate. Adhesion effect

In a preferred embodiment of the present invention, it is preferred that the tablet comprises a compound having an adhesive effect on the particulate matter forming the detergent matrix of the tablet. More preferably, higher levels of such compounds per unit weight are contained or present in the more elastic (i.e. less brittle) layer of the tablet detergent in order to obtain satisfactory elasticity without high compression. The adhesive effect on the particulate matter of the detergent matrix forming the tablet or the layer of the tablet is characterized by the need for force to break the tablet or layer based on the detergent matrix under examination pressed under controlled compression conditions. At a given compressive force, a high sheet or layer strength indicates that the particles are tightly adhered together during their compression, and thus a strong adhesion effect occurs. In Pharmaceutical docageforms, edited by h.a. lieberman et al: a method of estimating the strength of a tablet or layer (also known as the radial rupture stress) is given in the tablet (first roll, published 1989).

The adhesion effect was determined by comparing the strength of the sheet or layer of the raw base powder but without the compound having the adhesion effect with the strength of the sheet or layer of the powder mixture comprising 97 parts of the raw base powder and 3 parts of the compound having the adhesion effect. The compound having an adhesive effect is preferably added to the matrix in a substantially water-free form (water content below 10% (preferably below 5%)). The temperature of addition is 10 to 80 deg.C, more preferably 10 to 40 deg.C.

According to the present invention, a tablet having a detergent particulate material of 50g and a diameter of 55mm is defined to have an adhesive effect on the particulate material when the tablet tensile strength is increased by 30% (preferably 60 and more preferably 100%) by the presence of 3% of the compound having an adhesive effect in the base particulate material, given a compressive force of 3000N.

An example of a compound having an adhesive effect is sodium diisoalkylbenzene sulfonate.

When a surfactant is contained in a highly soluble compound that also has an adhesive effect on the particulate matter used to form the sheet or layer by compressing the particulate matter, the dissolution of the sheet or layer in an aqueous solution is greatly enhanced. In a preferred embodiment, at least 1% by weight of the tablet or layer is formed by the highly soluble compound, more preferably at least 2%, even more preferably at least 3% and most preferably at least 5% by weight of the tablet or layer is formed by the highly soluble compound having an adhesive effect on the particulate material.

It should be noted that compositions containing highly soluble compounds as well as surfactants are described in EP-A-0524075, which compositions are liquid compositions.

The highly soluble compounds having an adhesive effect on the particulate matter can give a detergent tablet having a higher tensile strength at a constant compressive force or an equivalent tensile strength at a lower compressive force, compared to conventional detergent tablets. Generally the entire sheet has a tensile strength of more than 5kPa, preferably more than 10kPa, more preferably more than 15kPa (particularly for laundry applications), even more preferably more than 30kPa and most preferably more than 50kPa (particularly for dishwasher or automatic dishwasher applications); and a tensile strength of less than 300kPa, preferably less than 200kPa, more preferably less than 100kPa, even more preferably less than 80kPa, and most preferably less than 60 kPa. In fact, in the case of laundry applications, the detergent tablets should be less compressed than in the case of e.g. automatic dishwashers (where dissolution is more accessible), and therefore in laundry applications it is preferred that the tensile strength is less than 30 kPa.

This makes it possible to produce tablets or layers having the same hardness or mechanical resistance as conventional tablet detergents, but with less compression of the tablet or layer (and therefore easier dissolution). Furthermore, since the compounds are highly soluble, the dissolution of the tablet or layer is in turn facilitated, with the result that the dissolution of the tablet-shaped detergent according to the invention is synergistically facilitated. Production of detergent tablets

In terms of the production of a single layer, the layer may be considered to be the sheet itself.

The tablet detergents of the invention may be prepared simply by mixing the solid ingredients together and compressing the mixture in a conventional tablet press (as used in the pharmaceutical industry). Preferably the base ingredient, in particular the gelling surfactant, is used in particulate form. Any liquid ingredient, such as a surfactant or suds suppressor, can be incorporated into the solid particulate ingredient in a conventional manner. Especially for laundry soaps in tablet form, the ingredients (e.g. builders and surfactants) can be spray dried in conventional manner and subsequently compressed under suitable pressure. Preferably the detergent tablet according to the invention is compressed with a force of less than 100000N, more preferably less than 50000N, even more preferably less than 5000N and most preferably less than 3000N. In practice, the most preferred embodiment is a detergent tablet suitable for laundry, compressed using a force of less than 2500N, but for example detergent tablets for automatic dishwashing machines are also contemplated, wherein such automatic dishwashing machine detergent tablets are typically more compressed than laundry soap tablets.

The particulate material used to prepare the detergent tablets of the invention may be prepared by any granulation or prilling method. Examples of such processes are spray drying (in co-current or counter-current spray drying towers), which generally result in lower bulk densities of 600g/L or less. The higher density particulate material may be granulated and densified in a high shear batch mixer/granulator or by a continuous granulation and densification process (e.g., using Lodige)^®CB and/or Lodige^®KM mixer). Other suitable methods include fluidized bed processes, powder extrusion processes (e.g., roller powder extrusion), extrusion, and any particulate material prepared by any chemical process (e.g., flocculation, crystallization, etc.). Single-leafThe vertical particles may also be any other particles, granules, pellets or granules.

The components of the particulate material may be mixed together by any conventional method. For example, the batch mode is suitable for use in concrete mixers, nauta mixers, ribbon mixers, or any other mixer. Alternatively, the mixing process may be carried out continuously by metering the weight of each component onto a conveyor belt and mixing them in one or more drums or mixers. A non-gelling binder may be sprayed onto some or all of the particulate matter component. The other liquid components may also be sprayed on the mixture of said components, either separately or after pre-mixing. For example, a perfume and fluorescer slurry may be sprayed. After spraying the binder (preferably towards the end of the treatment), finely divided flow aids (dusting agents such as zeolites, carbonates, silica) may be added to the particulate material to render the mixture less viscous.

The detergent tablets may be prepared by using any powder extrusion method, such as tabletting, briquetting or extrusion, preferably tabletting. Suitable equipment includes standard single stroke or rotary tablet presses (e.g., Courtoy)^®、Korch^®、Manesty^®Or Bonals^®). Preferably the tablets prepared according to the invention have a diameter of from 20mm to 60mm, preferably at least 35 to up to 55mm and a weight of from 25 to 100 g. Preferably the detergent tablets have a height to diameter (or width) ratio of greater than 1: 3, more preferably greater than 1: 2. The pressure required for preparing these tablets does not exceed 100000kN/m²Preferably not more than 30000kN/m²More preferably not more than 5000kN/m²Even more preferably not more than 3000kN/m²And most preferably not more than 1000kN/m². In a preferred embodiment according to the present invention, the tablet has a density of at least 0.9g/cc, more preferably at least 1.0g/cc, and preferably less than 2.0g/cc, more preferably less than 1.5g/cc, even more preferably less than 1.25g/cc and most preferably less than 1.1 g/cc.

Multilayer tablets are typically formed in a rotary tablet press by placing each layer of the matrix one after the other in a matrix positive feed bottle. As the process progresses, the base substrate is then laminated together in a pre-compressed or compressed state to form the multilayer sheet. In some rotary tablet presses it is also possible to compress the first feed layer before compressing the entire tablet. Hydrotrope compounds

In a preferred embodiment of the invention, a highly soluble compound having an adhesive effect is incorporated into the tablet of the invention, wherein the compound is also a hydrotrope compound. It is often advantageous to use such hydrotrope compounds to facilitate surfactant solubilization to avoid gelling, so that they are included in, for example, the lower elastic layer. The following specific compounds were defined as hydrotropes (see S.E.Friberg and M.Chiu, J.Dispersion Science and Technology, 9(5&6), pp. 443-:

1. a solution containing 25% by weight of the particular compound and 75% by weight of water was prepared.

2. Octanoic acid (added at a rate of 1.6 times the weight of the particular compound in solution) was then added to the solution, which was at a temperature of 20 ℃. The solution was mixed in a beaker equipped with a stirrer with a marine propeller (the paddle was about 5mm above the bottom of the Sotax beaker) and the rotation rate of the mixer was set at 200 revolutions per minute.

3. If the octanoic acid is completely solubilized, i.e. if the solution contains only one phase, the specific compound is a hydrotrope when the phase is a liquid phase. It should be noted that in a preferred embodiment of the invention, the hydrotrope compound is a flowable material prepared from solid particles at operating conditions of 15 to 60 ℃.

Hydrotrope compounds include the compounds listed below: see McCutcheon's Emulsifiers and Detergents (published by McCutcheon division of Manufacturing conditioners Company) for commercial hydrotropes. Related compounds also include: 1. a nonionic hydrotrope having the structure:

wherein R is C₈-C₁₀Alkyl chains, x is 1-15 and y is 3 to 10. 2. Such as the anion of an alkali metal aromatic sulfonate. This includes benzoic acid, salicylic acid, benzenesulfonic acid and many of its derivatives, naphthoic acid, and alkali metal salts of various hydrogenated aromatic acids. Examples of these are sodium, potassium and ammonium benzenesulfonates from the group consisting of toluenesulfonic acid, xylenesulfonic acid, isopropylbenzenesulfonic acid, 1,2, 3, 4-tetrahydronaphthalenesulfonic acid, naphthalenesulfonic acid, methylnaphthalenesulfonic acid, dimethylnaphthalenesulfonic acid, trimethylnaphthalenesulfonic acid.

Other examples include dialkyl benzene sulfonates such as diisopropylbenzene sulfonate, ethylmethylbenzene sulfonic acid, alkylbenzene sulfonic acids having an alkyl chain length of 3 to 10 (preferably 4 to 9) carbon atoms, linear or branched alkyl sulfonic acids having an alkyl chain of 1 to 18 carbon atoms. 3. Solvent hydrotropes such as alkoxylated glycerol and alkoxylated glycerides, ester slaloxylated glycerol, alkoxylated fatty acids, glycerides, polyglycerides. Preferred alkoxylated glycerols have the following structure:wherein 1, m, n are each a number from 0 to about 20, and 1+ m + n is from about 2 to about 60, preferably from about 10 to about 45 and R represents H, CH₃Or C₂H₅。

Preferred alkoxylated glycerols have the following structure:

in the formula R₁And R₂Each is C_nCOO or- (CH)₂CHR₃-O)₁-H, wherein R₃＝H、CH₃Or C₂H₅And 1 is a number from 1 to about 60, and n is a number from about 6 to about 24. 4. Polymeric hydrotropes such as those described in EP 636687:wherein E is a hydrophilic functional group, R is H or C₁-C₁₀Alkyl or is a hydrophilic functional group; r₁Is H, lower alkyl or aryl, R₂Is H, cycloalkyl or aryl, typically the polymer has a molecular weight of about 1000 to 1000000. 5. Abnormal structures such as 5-carboxy-4-hexyl-2-cyclohexen-1-yl octanoic acid (Diacid)^®) Hydrotrope of (1)

The use of such compounds in the present invention will further increase the dissolution rate of the tablet, for example as a hydrotrope compound which facilitates the dissolution of the surfactant. Such compounds may be formed from mixtures or from a single compound. Coating layer

The hardness of the tablets according to the invention can be improved by preparing coated tablets, the coating covering the non-coated tablets according to the invention, thus further improving the mechanical properties of the tablets while maintaining or further improving dissolution.

This is very advantageous for a multi-layer tablet according to the invention, wherein the mechanical properties of the higher elastic layer can be transferred to other parts of the tablet through the coating, thereby combining the advantages of the coating with the advantages of the higher elastic layer. Indeed, mechanical stress may be transmitted through the coating, thereby improving the mechanical integrity of the sheet.

In one embodiment of the invention, the detergent tablet may then be coated so that the tablet does not adsorb moisture, or absorbs moisture at a very slow rate. The coating is also so strong that only very low levels of breakage or abrasion occur under moderate mechanical shock to which the detergent tablet is subjected during handling, packaging and shipping. Finally it is preferred that the coating is so brittle that it breaks when the tablet is subjected to strong mechanical shock. In addition, it is advantageous if the coating is dissolved under alkaline conditions or easily emulsified by surfactants. This avoids the problem of visible residues in the window of a front-loading washing machine during the wash cycle and avoids the sedimentation of insoluble particles or clots of coating material in the washing machine load.

The water solubility was determined according to the following ASTM E1148-87 test procedure, entitled "Standard method for measuring Water solubility". 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 thereof.

Preferably the coating material has a melting point of 40 ℃ to 200 ℃.

The coating may be applied in a variety of ways. Two preferred coating methods are a) coating with a molten substance and b) coating with a solution of said substance.

In a), the coating material is applied at a temperature above the melting point of the coating material and cured on the sheet. In b), the coating is applied as a solution and the solvent is dried to leave a coherent coating. The substantially insoluble substance may be applied to the sheet, for example by spraying or dipping. Typically, the molten material will rapidly solidify to form an adherent coating when sprayed onto the tablet. When the detergent tablet is dipped into the molten mass and subsequently removed, rapid cooling results in rapid solidification of the coating mass. It is clear that substantially insoluble materials having a melting point below 40 ℃ do not solidify sufficiently at room temperature and we have found that materials having a melting point above about 200 ℃ cannot be used in practice. Preferably the material melts at between 60 ℃ and 160 ℃, more preferably between 70 ℃ and 120 ℃.

The term "melting point" refers to the temperature at which the substance is slowly heated, for example in a capillary tube, to become a transparent liquid.

Any desired thickness of the coating may be applied according to the present invention. For most applications, the coating forms from 1% to 10%, preferably from 1.5% to 5%, by weight of the sheet.

The coating of the sheet of the invention is very hard and provides the sheet with additional strength.

In a preferred embodiment of the invention, the cracking of the coating in the wash is improved by adding a disintegration agent to the coating. The disintegrant will swell upon contact with water and break the coating into small pieces. This will improve the dissolution of the coating in the wash solution. The decomposing agent is suspended in the coating melt in a content of at most 30%, preferably 5% to 20%, most preferably 5 to 10% by weight. Possible decomposition agents are described in Handbook of pharmaceutical Excipients (1986). Examples of suitable disintegrating agents include starch: native, modified or pregelatinized starch, sodium starch gluconate; gum: agar gum, guar gum, locust bean gum, karaya gum, pectin gum, tragacanth gum; croscarmylose sodium, crospovidone, cellulose, carboxymethylcellulose, alginic acid and its salts (including sodium alginate), silica, clay, polyvinylpyrrolidone, soybean polysaccharide, ion exchange resins, and mixtures thereof. Tensile strength

In terms of measuring the tensile strength of a layer, the layer can be considered to be the sheet itself.

Depending on the composition of the raw material and the shape of the tablet, the compression force used can be adjusted to have no effect on the tensile strength and the disintegration time in the washing machine. The process can be used to make uniform or layered sheets of any size or shape.

For cylindrical sheets, the tensile strength corresponds to the radial rupture stress (DFS, which is one way of expressing the strength of a sheet or layer) and is determined by the following equation:

tensile strength 2F/pi Dt formula where F is the maximum force (newtons) that causes tensile failure (fracture) was measured by a VK200 sheet hardness tester (supplied by Van Kell industries inc.). D is the diameter of the sheet or layer and t is the thickness of the sheet or layer. For non-circular patches, π D may simply be replaced by the perimeter of the patch. (Method Pharmaceutical Dosage Forms: tables, volume 2, pages 213 to 217). A sheet having a radial rupture stress of less than 20kPa is considered brittle and tends to result in some rupture of the sheet upon delivery to the consumer. Preferably a radial rupture stress of at least 25 kPa.

The definition of tensile strength of a non-cylindrical type sheet (where the cross section perpendicular to the height of the sheet is not circular and where a force is applied in the direction perpendicular to the height of the sheet and to the side of the sheet perpendicular to the non-circular cross section) is similar. Detergent tablet dosing

The dosing rate of the detergent tablets can be determined as follows:

two tablets, nominally 50g each, were weighed and subsequently placed in a Baucknecht^®Feed for WA9850 washing machineIn the device. The water supply to the washer was set at a temperature of 20 c and a hardness of 21 grains per gallon, and the feeder water inlet flow rate was set at 8L/min. The residual content of the tablets in the feeder was checked by turning on the washing machine and setting the wash cycle to wash program 4 (white/color, short cycle). The percent residue of the feed was determined as follows:

percent feed ═ weight of residue x 100/weight of original tablet

The level of residue was determined by repeating the method 10 times and calculating the average residue level from the 10 independent measurements. A 40% residue by weight of the original sheet was considered acceptable in this stress test. Preferably less than 30% and more preferably less than 25% residue.

It should be noted that the measurements given for water hardness are in the traditional "grains/gallon" unit,wherein 0.001 mol/l is 7.0 grains/gallon, which represents Ca in the solution²⁺The concentration of (c). Foaming agent (effervescence)

In another preferred embodiment of the invention, the tablet further comprises a sudsing agent.

Foaming, as defined herein, refers to the release of gas bubbles from a liquid as a result of the chemical reaction of a soluble acid source with an alkali metal carbonate to produce carbon dioxide gas.

Namely, it is

Other examples of acid and carbonate sources and other blowing agent systems are found in: (Pharmaceutical document Forms: tables, volume 1, pages 287 to 291).

In addition to the detergent ingredients, a sudsing agent may be added to the detergent tablet mixture. The addition of a foaming agent to the tablet improves the disintegration time of the tablet. Preferably the sudsing agent is added in an amount of from 5 to 20% and most preferably from 10 to 20% by weight of the tablet detergent, preferably as agglomerates of different particles or as compacts rather than discrete particles.

The tablet may have a higher d.f.s due to the gas generated by the blowing agent in the tablet and still have the same decomposition time as without the blowing agent. The decomposition of the tablet with blowing agent will be faster when the d.f.s of the tablet with blowing agent remains the same as the tablet without blowing agent.

Additional dissolution aids may be provided by using compounds such as sodium acetate or urea. Suitable dissolution aids can also be found in pharmaceutical dosage Forms, edited by H.A Lieberman et al: tablets, volume 1, second edition, ISBN 0-8247-8044-2. Detersive surfactant

According to the invention, a surfactant is contained in the tablet. The addition of highly soluble compounds facilitates the dissolution of the surfactant.

Non-limiting examples of surfactants useful herein (generally present in amounts of about 1% to about 55% by weight) include conventional C₁₁-C₁₈Alkyl benzene sulfonates ("LAS") and branched and random C₁₀-C₂₀Primary alkyl sulfates of the formula ("AS"), CH₃(CH₂)_x(CHOSO₃-M⁺)CH₃And CH₃(CH₂)_y(CHOSO₃-M⁺)CH₂CH₃(wherein x and (y +1) are at least about 7, preferablySelected from an integer of at least about 9, and M is a water-soluble cation (especially sodium) C₁₀-C₁₈Secondary (2, 3) alkyl sulfates, unsaturated sulfates such as oleyl sulfate, C₁₀-C₁₈Alkyl alkoxy sulfates of (AE) ("AE)_xS "; in particular EO1-7 ethoxysulfate), C₁₀-C₁₈Alkyl alkoxy carboxylates (especially EO1-5 ethoxy carboxylates), C₁₀-C₁₈Glyceryl ether, C₁₀-C₁₈Alkyl polyglucosides and their corresponding sulfuric acid polyglucosides and C₁₂-C₁₈α -sulfonated fatty acid ester if desired, conventional nonionic and amphoteric surfactants such as C can be included in the overall composition₁₂-C₁₈Alkyl ethoxylates ("AE", including so-called narrow peak alkyl ethoxylates and C₆-C₁₂Alkylphenol alkoxylates (in particular ethoxylates and mixed ethoxy/propoxy oxides)Object)), C₁₂-C₁₈Betaines and sulfobetaines ("sulfobetaines"), C₁₀-C₁₈Amine oxides of (2), and the like. Also usable are C₁₀-C₁₈N-alkyl polyhydroxy fatty acid amides. Typical examples include C₁₂-C₁₈N-methylglucamides (see WO9,206,154). Other sugar-derived surfactants include N-alkoxy polyhydroxy fatty acid amides, such as C₁₀-C₁₈N- (3-methoxypropyl) glucamide. N-propyl to N-hexyl C may be used₁₂-C₁₈The glucamide of (a) is low foaming. Conventional C may also be used₁₀-C₂₀Soap. If high foaming is desired, a branched chain C may be used₁₀-C₁₆Soap. Mixtures of anionic and nonionic surfactants are particularly useful. Other conventionally useful surfactants are listed in standard texts. In a preferred embodiment, the tablet contains at least 5% by weight surfactant, more preferably at least 15% by weight, even more preferably at least 25% by weight and most preferably from 35% to 45% by weight surfactant. Non-gelling binders

To further facilitate dissolution, a non-gelling binder may be incorporated into the particles forming the sheet.

If a non-gelling binder is used, suitable non-gelling binders include synthetic organic polymers such as polyethylene glycol, polyvinylpyrrolidone, polyacrylates, and water-soluble acrylate copolymers. The following binder types were found in Handbook of Pharmaceutical Excipients (second edition): acacia, alginic acid, acrylic acid polymers, sodium carboxymethylcellulose, dextrin, ethylcellulose, gelatin, guar gum, hydrogenated vegetable oil type I, hydroxyethyl cellulose, hydroxypropyl methylcellulose, liquid glucose, magnesium aluminum silicate, maltodextrin, methylcellulose, polymethacrylates, polyvinylpyrrolidone, sodium alginate, starch, and zein. Most preferred binders also have an active cleaning function in laundry, such as cationic polymers, i.e. ethoxylated hexamethylene diamine quaternary compounds, bis-hexamethylene triamine or other polymers such as pentamine, ethoxylated polyvinyl amine, maleic diacrylic acid.

Preferably, the non-gelling binder material is sprayed, so that it should have a melting temperature suitably below 90 ℃, preferably below 70 ℃ and even more preferably below 50 ℃ so as not to damage or degrade the other active ingredients in the matrix. Most preferred are nonaqueous liquid binders (i.e., not in aqueous solution) that can be sprayed in molten form. However, they may also be solid binders which are incorporated into the matrix by dry addition but which have adhesive properties in the sheet.

Preferably the non-gelling binder material is used in an amount of 0.1 to 15% of the composition, more preferably below 5% and in particular below 2% by weight of the tablet if it is a non-detergent active.

Gelling binders (e.g., nonionic surfactants) in liquid or molten form are preferably avoided. The compositions do not exclude nonionic surfactants and other gelling binders, but preferably they are processed into the tablet as a particulate rather than as a liquid component. Builder

The compositions herein may optionally include builders to assist in controlling the hardness of the minerals. Inorganic and organic builders can be used. Builders are commonly used in fabric laundry compositions to aid in the removal of particulate soils.

The level of builder may vary widely depending on the end use of the composition.

Inorganic or phosphorus-containing builders include, but are not limited to, alkali metal, ammonium and alkanolammonium salts of polyphosphoric acids (exemplified by triphosphates, pyrophosphates, and glassy polymer metaphosphates), phosphonic acids, phytic acids, silicic acids, carbonic acids (including bicarbonates and sesquicarbonates), sulfuric acid, and aluminosilicates. However, in some cases non-phosphate builders are required. Importantly, the compositions herein perform surprisingly even in the presence of so-called "weak" builders (as compared to phosphates), such as citric acid, or in the case of so-called "under-built" (as occurs with zeolite or layered silicate builders).

Examples of silicate builders are alkali metal silicasAcid salts, in particular those having SiO₂∶Na₂Alkali metal silicates and layered silicates having an O ratio of 1.6: 1 to 3.2: 1, such as the layered sodium silicate described in U.S. patent 4,664,839 issued to h.p. rieck at 12 months 5 1987. The crystalline layered silicate marketed by Hoechst is under the trade name NaSKS-6 (often abbreviated herein as "SKS-6"). Unlike zeolite builders, the NaSKS-6 silicate builder is free of aluminum. NaSKS-6. delta. -Na with layered silicate₂SiO₅Morphological forms. They can be prepared by processes as described in DE-A-3,417,649 and DE-A-3,742,043. SKS-6 is a highly preferred layered silicate for use herein, but those having the general formula NaMSi may also be used_xO_2x+1·yH₂(ii) layered silicates of the formula O (where 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 is used herein.) various other layered silicates from Hoechst include α, β and the gamma forms NaSKS-5, NaSKS-7 and NaSKS-11. As noted above, it is most preferred to use delta-Na herein₂SiO₅(NaSKS-6 form). Other silicates such as magnesium silicate may also be used, which are used in granular formulations as a profile weighting agent (crispening agent), as a stabilizer for oxygen bleaches, and as a component of a bubble control system.

Examples of carbonate builders are alkaline earth and alkali metal carbonates as disclosed in German patent application No. 2,321,001 (published on 1973, 11/15).

Aluminosilicate builders can be used in the present invention. Aluminosilicate builders are of great importance in many of the cotton granular detergent compositions currently on the market, as well as being a major builder component in liquid detergent formulations. Aluminosilicate builders include those having the illustrative formula:

[M_z(zAlO₂)_y]·xH₂O

wherein z and y are integers of at least 6, the molar ratio of z to y is from 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 may be crystalline or amorphous in structure and may be derived from naturally occurring or synthetic sources. One method of producing aluminosilicate ion exchange materials is disclosed in U.S. patent 3,985,669 issued to Krummel et al at 10/12/1976. Preferred synthetic crystalline aluminosilicate ion exchange materials useful herein are available under the trade designations Zeolite A, Zeolite P (B), Zeolite MAP and Zeolite X. In a particularly preferred embodiment, the crystalline aluminosilicate example exchange material has the formula:

Na₁₂[(AlO₂)₁₂(SiO₂)₁₂]·xH₂wherein x is about 20 to about 30, particularly about 27. This material is referred to as zeolite a. Dehydrated zeolites (x ═ 0 to 10) may also be used herein. Preferably, the aluminosilicate has a particle size of about 0.1 to 10 μm in diameter.

Organic builders suitable for use in the present invention include, but are not limited to, various polycarboxylate compounds. As used herein, "polycarboxylate" refers to compounds having a plurality of carboxylate groups, preferably at least 3 carboxylate groups. Polycarboxylate builders can generally be added to the compositions in the acid form, but can also be added in the form of neutralized salts. When salt forms are used, alkali metal salts such as sodium, potassium and lithium or alkanolammonium salts are preferred.

The polycarboxylate builders include a variety of useful material types. One important class of polycarboxylate builders includes the ether polycarboxylates, including oxydisuccinates (oxy-disuccinates) (e.g., U.S. Pat. No. 3,128,287 issued to Berg 4/7 in 1964 and U.S. Pat. No. 3,635,830 issued to Lamberti et al 1/18 in 1972, also see the "TMS/TDS" builder in U.S. Pat. No. 4,663,071 to Bush et al 5/5 in 1987). Suitable ether polycarboxylates also include cyclic compounds, particularly cycloaliphatic compounds such as those described in U.S. Pat. Nos. 3,923,679, 3,835,163, 4,158,635, 4,120,874 and 4,102,903.

Other suitable builders include the various alkali metal, ammonium and substituted ammonium salts of ether polycarboxylates, copolymers of maleic anhydride with ethylene or vinyl methyl ether, 1,3, 5-trihydroxybenzene-2, 4, 6-trisulfonic acid and carboxymethyloxysuccinic acid, polyacetic acids such as ethylenediaminetetraacetic acid and nitrilotriacetic acid, and polycarboxylates such as mellitic acid, succinic acid, oxydisuccinic acid, polymaleic acid, benzene 1,3, 5-tricarboxylic acid, carboxymethyloxysuccinic acid, and soluble salts thereof.

Citrate builders such as citric acid and soluble salts thereof (especially sodium salts) are polycarboxylate builders of particular importance for use in cotton liquid detergents because of their availability from renewable sources and their biodegradability. Citrate salts may also be used in granular compositions, particularly in combination with zeolite and/or layered silicate builders. Oxydisuccinates are particularly useful in such compositions and mixtures.

3, 3-dicarboxy-4-oxa-1, 6-adipate and related compounds disclosed in U.S. patent 4,566,984 issued to Bush on 28.1.1986 are also suitable for use in the detergent compositions of the present invention. Useful succinic acid builders include C₅-C₂₀Alkyl and alkenyl succinic acids and salts thereof. A particularly preferred compound of this type is dodecylsuccinic acid. Specific examples of succinate builders include: lauryl succinic acid, myristyl succinate, cetyl succinate, 2-dodecyl succinate (preferred), 2-pentadecyl succinate and the like. Lauryl succinate is among the preferred builders described in European patent application 86200690.5/0,200,263, published on 5.11.1986.

Other suitable polycarboxylates are described in U.S. Pat. No. 4,144,226 to Crutchfield et al, 3/13 1979, and U.S. Pat. No. 3,308,067 to Diehl, 3/7 1967. See also U.S. patent 3,723,322 to Diehl.

Fatty acids, e.g. C, can be substituted₁₂-C₁₈Monocarboxylic acids are incorporated into the composition either alone or in combination with the aforementioned builders, especially citrate and/or the succinic acid builder, to provide additional building activity. Such use of fatty acids will generally result in reduced foaming, which the formulator should take into account.

Where phosphorus-based builders can be used, and particularly in the formulation of bar soaps for hand-washing operations, a variety of alkali metal phosphates can be used, such as the well-known sodium tripolyphosphates, pyrophosphates, and orthophosphates. Sodium phosphonate builders such as ethane-1-hydroxy-1, 1-diphosphonate and other known phosphonates may also be used (see, for example, U.S. patents 3,159,581, 3,213,030, 3,422,021, 3,400,148 and 3,422,137). Bleaching agent

The detergent compositions herein may optionally contain a bleaching agent or a bleaching composition comprising a bleaching agent and one or more bleach activators. When present, the bleaching agent used in fabric washing is preferably present at a level of from about 1% to about 30%, more preferably from about 5% to about 20% of the detergent composition. If present, the bleach activator is preferably present in an amount of from about 0.1% to about 60%, more preferably from about 0.5% to about 40%, of the bleaching composition (including bleach plus bleach activator).

The bleaching agent used herein may be any bleaching agent (known or to be known) used in detergent compositions for textile cleaning, hard surface cleaning or other cleaning purposes. These include oxygen bleaches and other bleaching agents. Perborate bleaching agents such as sodium perborate (e.g., monohydrate or tetrahydrate) may be used herein.

Another useful class of bleaching agents (which is limiting) includes percarboxylic acid bleaching agents and salts thereof. Suitable examples of such agents include magnesium monoperoxyphthalate hexahydrate, the magnesium salt of m-chloroperbenzoic acid, 4-nonylamino-4-oxoperoxybutyric acid and diperoxydodecanedioic acid. Such bleaches are disclosed in U.S. Pat. No. 4,483,781 (Hartman, 11/20 1984), U.S. patent application 740,446(Burns et al, 3/6 1985), European patent application 0,133,354(Bank et al, 2/20 1985), and U.S. Pat. No. 4,412,934 (Chung et al, 11/1 1983). Highly preferred bleaching agents also include 6-nonylamino-6-oxoperoxyhexanoic acid, described in U.S. Pat. No. 4,634,551 (issued to Burns et al on 6.1.1987).

Peroxygen bleaches may also be used. Suitable peroxygen bleach compounds include sodium bicarbonate peroxygen and equivalent amounts of "percarbonate" bleaches, sodium pyrophosphate peroxygen, urea peroxygen and sodium peroxide. Persulfate bleach (e.g., OXONE, commercially produced by DuPont) may also be used.

Preferred percarbonate bleach compositions contain dry particles having an average particle size of from about 500 μm to about 1,000 μm, no more than about 10% by weight of the particles being less than about 200 μm and no more than about 10% by weight of the particles being greater than about 1,250 μm. Optionally, the percarbonate may be coated with silicates, borates or water soluble surfactants. Percarbonate is available from various commercial sources such as FMC, Solvay and Tokai Denka.

Mixtures of bleaching agents may also be used.

Preferably, peroxygen bleach, perborates, percarbonates, etc., are used in conjunction with a bleach activator, resulting in the generation of an aqueous solution of the peroxyacid corresponding to the bleach activator in situ (i.e., during the wash). Non-limiting examples of various active agents are disclosed in U.S. Pat. No. 4,915,854 (issued to Mao et al on 4.4.10.1990) and U.S. Pat. No. 4,412,934. Typically, the Nonanoyloxybenzenesulfonate (NOBS) and Tetraacetylethylenediamine (TAED) actives, and mixtures thereof, may also be used. See also U.S.4,634,551 for other typical bleaching and active agents that may be used herein.

Highly preferred amide derived bleach activators have the formula:

R¹N(R⁵)C(O)R²c (O) L or R¹C(O)N(R⁵)R²C (O) L wherein R¹Is an alkyl group containing from about 6 to about 12 carbon atoms, R²Is alkylene containing 1 to about 6 carbon atoms, R⁵Is H or an alkyl, aryl or alkaryl group containing from about 1 to about 10 carbon atoms, and L is any suitable leaving group. A leaving group is a group that leaves the bleach activator as a result of nucleophilic attack of the perhydrolysis (perhydrolysis) anion on the bleach activator. A preferred leaving group is phenyl sulfonate.

Examples of preferred bleach activators in the above formula include (6-octanoylamide-hexanoyl) oxybenzene sulfonate, (6-nonanamido hexanoyl) oxybenzene sulfonate, (6-decanoylamide-hexanoyl) oxybenzene sulfonate and mixtures thereof as described in U.S. Pat. No. 4,634,551, herein incorporated by reference.

Another class of bleach activators includes the benzoxazine-type activators disclosed by Hodge et al in U.S. patent 4,966,723 (incorporated herein by reference) issued 10, 30, 1990. One highly preferred benzoxazine-based active agent is:yet another preferred class of bleach activators includes acyl lactam activators, particularly acyl caprolactams and acyl valerolactams of the formula:

in the formula R⁶Is H or an alkyl, aryl, alkoxyaryl or alkylaryl group containing from 1 to about 12 carbon atoms. Highly preferred lactam actives include benzoyl caprolactam, octanoyl caprolactam, 3,5, 5-trimethylhexanoyl caprolactam, nonanoyl caprolactam, decanoyl caprolactam, undecanoyl caprolactam, benzoyl valerolactam, octanoyl valerolactam, decanoyl valerolactam, undecanoyl valerolactam, nonanoyl valerolactam, 3,5, 5-trimethylhexanoyl valerolactam and mixtures thereof. See U.S. patent 4,545,784 to Sanderson, 10/8/1985, which is incorporated herein by reference, which discloses absorption of acetyl caprolactam (including benzoyl caprolactam) into sodium perborate. Bleaching agents other than oxygen bleaching agents are known in the art and may be used herein. One type of non-oxygen bleaching agent of particular interest includes photoactivated bleaching agents such as sulfonated zinc and/or aluminum phthalocyanine. See U.S. Pat. No. 4,033,718 to Holcomb et al, 1977, 7, 5. If used, the detergent compositions will generally contain from about 0.025% to about 1.25% by weight of such bleaching agents, especially zinc sulfonated phthalocyanine.

If desired, the bleaching compound may be catalysed by means of a manganese compound. Such compounds are well known in the art and include, for example, those disclosed in U.S. Pat. No. 5,246,621, U.S. Pat. No. 5,244,594, U.S. Pat. No. 5,194,416, U.S. Pat. No. 5,114,606 and European patent application publication Nos. 549,271A1, 549,272A1, 544,440a2 and 544,490a 1; preferred examples of these catalysts include Mn^IV ₂(u-O)₃(1, 4, 7-trimethyl-1, 4, 7-triazacyclononane)₂(PF₆)₂、Mn^III ₂(u-O)₁(u-OAc)₂(1, 4, 7-trimethyl-1, 4, 7-triazacyclononane)₂-(ClO₄)₂、Mn^IV ₄(u-O)₆(1, 4, 7-triazacyclononane)₄(ClO₄)₄、Mn^IIIMn^IV ₄(u-O)₁(u-OAc)₂- (1, 4, 7-trimethyl-1, 4, 7-triazacyclononane)₂(ClO₄)₃、Mn^IV(1, 4, 7-trimethyl-1, 4, 7-triazacyclononane) - (OCH₃)₃(PF₆) And mixtures thereof. Other metal-based bleach catalysts include those disclosed in U.S. Pat. No. 4,430,243 and U.S. Pat. No. 5,114,611. The following U.S. patents also reportManganese is used with various complexing ligands to enhance bleaching: 4,728,455, 5,284,944, 5,246,612, 5,256,779, 5,280,117, 5,274,147, 5,153,161 and 5,227,084.

As one implementation (not intended to be limiting), the compositions and methods can be adapted to provide at least ten million parts of the active bleach catalyst material in the aqueous wash liquor, and preferably from about 0.1ppm to about 700ppm, more preferably from about 1ppm to about 500ppm of the catalyst material in the laundry liquor. Enzyme

Enzymes may be included in the formulations herein for various fabric laundering objectives, including, for example, removal of protein-based, carbohydrate-based, or triglyceride-based stains, and inhibition of dye transfer and fabric refreshment. Enzymes that may be incorporated include proteases, amylases, lipases, cellulases, and peroxidases, and mixtures thereof. Other types of enzymes may also be included. They may be from any suitable source such as plants, animals, bacteria, fungi and yeasts. However, their selection is governed by several factors such as optimum pH activity and/or stability, thermal stability, stability towards various active detergents, builders, etc. Bacterial or fungal enzymes, such as bacterial amylases and proteinases and fungal cellulases are preferred in this respect.

Typically, the enzyme is incorporated in an amount sufficient to provide up to about 5mg, more preferably from about 0.01mg to about 3mg, of active enzyme per gram of the composition. In other words, the compositions generally contain from about 0.001% to about 5%, preferably from 0.01% to 1%, by weight of the commercial enzyme preparation. The protease enzyme is typically present in such commercial preparations in an amount sufficient to provide an activity of 0.005 to 0.1Anson Units (AU) per gram of the composition.

Suitable proteases are subtilisins obtained from specific strains of Bacillus subtilis and Bacillus licheniformis. Another suitable protease is obtained from a strain of Bacillus and has maximum activity over the entire pH range of 8 to 12, developed by Novo industries A/S and sold under the trade name ESPERASE. The preparation of this and similar enzymes is described in British patent Specification 1,243,784 to Novo. Commercial products of proteolytic enzymes suitable for removal of protein-based stains include ALCALASE and SAVINASE sold from Novo Industries A/S (Denmark) and MAXATASE sold from International Bio-Synthesis, Inc (the Netherlands). Other proteases include protease A (see European patent application 130,756, published on 9.1.1985) and protease B (see European patent application Ser. No. 87303761.8, filed on 28.4.1987 and European patent application 130,756, Bott et al, published on 9.1.1985).

Amylases include, for example, α -amylase (described in British patent Specification No. 1,296,839(Novo)), commercially available as RAPIDASE (International Bio-Synthesis, Inc.) and TERMAMYL (Novo industries).

Cellulases usable in the present invention include bacterial cellulases or fungal cellulases. Preferably they have an optimum pH between 5 and 9.5. Suitable cellulases are disclosed in U.S. patent No. 4,435,307 issued to Barbesgoard et al at 3/6 1984, which discloses the production of fungal cellulases from Humicola (Humicola insolens) and Humicola strain DSM1800, or cellulase 212 producing a fungus belonging to the genus aeromonas and cellulase extracted from the liver pancreas of marine mollusks, respectively. Suitable cellulases are also disclosed in GB-A-2.075.028, GB-A-2.095.275 and DE-OS-2.247.832, CAREZYME (Novo) being particularly useful.

Lipases suitable for detergents include those produced by microorganisms of the genus Pseudomonas, such as Pseudomonas stutzeri (Pseudomonas stutzeri) ATCC19.154 as disclosed in British patent 1,372,034. See also lipase, published in the public consulted Japanese patent application 53,20487, 2, 24, 1978. This lipase is available under the trade name lipase P "Amano" (hereinafter referred to as "Amano-P") from Amano pharmaceutical Co.Ltd. of Nagoya, Japan. Other suitable commercial lipases include Amano-CES, lipases derived from Chromobacterium viscosum (Chromobacterium viscosum) such as the Chromobacterium viscosum variant LipofencR.3673 from Toyo Jozo Co., Tagata, Japan; chromobacterium viscosum lipases from U.S. Biochemical Corp. and Disoynth Co. of the Netherlands and lipases from Pseudomonas gladioli. Preferred for use herein is the LIPOLASE enzyme commercially available from Novo (see also EPO341,947) and derived from Humicola langinosa.

Peroxidase enzymes are used in conjunction with oxygen sources such as percarbonates, perborates, persulfates, hydrogen peroxide, and the like. They are used for "solution bleaching", i.e. to prevent dyes or pigments removed from a substrate during a washing process from transferring to other substrates in the wash solution. Peroxidases are familiar to those skilled in the art and include, for example, horseradish peroxidase, ligninase and haloperoxidase such as chloro-and bromo-peroxidase. Detergent compositions containing peroxidase are disclosed in, for example, PCT International application WO89/099813, published at 19/10/1989, transferred by O.Kirk to Novo Industries A/S.

Various enzymatic materials and methods for their incorporation into synthetic detergent compositions are also disclosed in U.S. patent 3,553,139 issued to McCarty et al, 1, 5, 1971. Also disclosed in Place et al, U.S. Pat. No. 4,101,457 at 18.7.1978 and U.S. Pat. No. 4,507,219 at 26.3.1985 to Hughes. Enzyme materials useful in liquid detergent formulations and their incorporation into such formulations are disclosed in U.S. patent 4,261,868 issued to Hora et al, 4/14, 1981. Enzymes used in detergents can be stabilized by various techniques. Enzyme stabilization techniques are disclosed and exemplified in U.S. Pat. No. 3,600,319 issued to Gedge et al at 8.17.1971 and in European patent application publication No. 0199405, application No. 86200586.5 to Venegas at 10.29.1986. Enzyme stabilization systems are also described, for example, in U.S. Pat. No. 3,519,570.

Other ingredients commonly used in detergent compositions and which may be incorporated in the tablet detergents of the invention include chelating agents, soil release agents, stain anti-redeposition agents, dispersants, brighteners, suds suppressors, fabric softeners, dye transfer inhibitors and perfumes. Washing method

It is known to place conventional laundry detergent tablets in the drum of a washing machine together with the laundry. However, this approach can result in unsightly residues being visible in the window of the washing machine, particularly in certain types of washing machines designed for lower water consumption operation. More extreme is the fact that there is still residue on the laundry after the end of the laundering cycle due to incomplete dissolution.

The tablets according to the invention can be used according to laundry methods which largely avoid this. The novel process comprises preparing an aqueous solution of a detergent tablet for use in a washing machine, wherein the aqueous solution of the laundry detergent is formed by dissolving a tablet according to the invention in water.

The preferred process more particularly relates to the preparation of an aqueous laundry detergent solution for a front-loading washing machine having a formulation box and a washing drum, wherein the aqueous laundry detergent solution is formed by dissolving a tablet according to the invention in water, characterised in that the tablet is placed in the formulation box and water is passed through the formulation box so that the tablet is dosed as an aqueous laundry detergent solution, and the aqueous solution is subsequently passed through the washing drum.

Examples example 1i) washing of powders based on composition C (see table below) was prepared as followsPreparation: the particulate matter of the total raw material composition is mixed together in a mixing or throwing cylinder to obtain a homogeneous particulate mixture. During the mixing process, spraying of the binder system is carried out. After this stage, the matrix was separated into two different samples. The DIBS-adhering hydrotrope was added to only one of the samples and then separately at Loedige KM 600^®And (4) treating. For a two-layer tablet, the layer with DIBS is used as the lower layer of higher elasticity and the layer without DIBS is used as the more brittle upper layer. ii) use of Bonals^®The tablet press was rotated to load the two matrices into two separate positive feed bottles. The substrates with DIBS were loaded first onto the turntable table, followed by the second substrate (substrate without DIBS). The two layers are compressed together in a pre-compressed and compressed state to form a bi-layer panel having a relatively high elastic bottom layer. iii) in this particular embodiment, the sheet has a rectangular cross-section of 62.5 x 38.5mm, a height of 20.5mm and a weight of 48 g. The height of the bottom layer corresponds to 25% of the total height of the sheet. If the circular sheet is constructed from an underlying substrate of the same density (983g/L) as the rectangular sheet, the tensile strength of the layer is 7.8 kPa. Using the same experiment (for a density of 991g/L), the upper layer of the sheet had an equivalent tensile strength of 5.1 kPa. The elasticity test gave a value of 1.8J/kN for the upper layer and a value of 3.3J/kN for the bottom layer. iv) for comparison of the tests, a tablet press with the same pressure setting but the base was usedBoth layers of the body contained no DIBS preparation tablets. The sheet had a density (991g/L) and strength identical to the upper layer of the two-layer sheet. Wherein the dual layer tablet and the comparative tablet differ only in that the dual layer tablet has a bottom layer prepared compositionally using a base of DIBS. v) to demonstrate the fact that the elastic bottom layer improves the resistance on the production line, the comparative and the double-layer sheets were transported through a series of rolling belts on the production line and then individually analyzed for the degree of fracture. More than 100 pieces were prepared per series and analyzed. vi) to demonstrate that the properties of the formulation are not affected by the resilient under-layer, the standard formulation test described above was usedThe test was performed on 10 pieces each. vii) we found differences between the bilayer tablet and the comparative tablet. Most of the comparative sheets were severely damaged at the bottom layer (the portion of the sheet contacting the rolling belt and the general belt), while the two-layer sheet having a higher elastic bottom layer was hardly damaged. One significant difference is that the number of cleaved pieces is greatly reduced. The dosing properties of the double layer tablet are not affected by the higher elasticity bottom layer. The following table summarizes the results of the tests performed.

Sheet type	With a damaged sole The slice% of the layer	Broken pieces%	Dosing residue ％
				Comparison	98％	18％	1.8％
Double layer	10％	5％	2.5％

The following are examples of raw particulate material compositions useful in making laundry detergent tablets according to the present invention in which the more resilient layer is more compressed than the more brittle layer, or in which different compositions may be used or adapted for each layer.

	Composition A (% (by weight))
		Anionic agglomerates 1	21.45
Anionic agglomerates 2	13.00
		Cationic agglomerates	5.45
Layered silicate	10.8
		Sodium percarbonate	14.19
Bleach activator agglomerates	5.49
		Sodium carbonate	13.82
EDDS/sulfate particles	0.47
		Hydroxy ethane diphosphonic acid tetrasodium salt	0.73
Soil release polymers	0.33
		Fluorescent agent	0.18
Encapsulated sulfonated zinc phthalocyanines	0.025
		Soap powder	1.40
Suds suppressor	1.87
		Citric acid	7.10
Protease enzyme	0.79
		Lipase enzyme	0.28
Cellulase enzymes	0.22
		Amylase	1.08
Binder spraying system	1.325
		Total amount of	100.00

The anionic agglomerate 1 contains 40% anionic surfactant, 27% zeolite and 33% carbonate.

The anionic agglomerate 2 contains 40% anionic surfactant, 28% zeolite and 32% carbonate.

The cationic agglomerates contained 20% cationic surfactant, 56% zeolite and 24% sulfate.

The layered silicate contains 95% SKS6 and 5% silicate.

The bleach activator agglomerate contains 81% TAED, 17% acrylic acid/maleic acid copolymer (acid form) and 2% water.

The ethylenediamine N, N-disuccinate/sulfate particles contained 58% ethylenediamine N, N-disuccinate, 23% sulfate and 19% water.

The encapsulated sulfonated zinc phthalocyanine was 10% active.

The suds suppressor contained 11.5% silicone oil (from Dow Corning), 59% zeolite, and 29.5% water.

The binder spray system contained 50% Lutensit K-HD96 and 50% PEG (polyethylene glycol).

	Composition B (% (by weight))
		Anionic agglomerates 1	21.45
Anionic agglomerates 2	13.00
		Cationic agglomerates	5.45
Layered silicate	10.8
		Sodium percarbonate	14.19
Bleach activator agglomerates	5.49
		Sodium carbonate	12.645
EDDS/sulfate particles	0.47
		Hydroxy ethane diphosphonic acid tetrasodium salt	0.73
Soil release polymers	0.33
		Fluorescent agent	0.18
Encapsulated sulfonated zinc phthalocyanines	0.025
		Soap powder	1.40
Suds suppressor	1.87
		Citric acid	7.10
Protease enzyme	0.79
		Lipase enzyme	0.28
Cellulase enzymes	0.22
		Amylase	1.08
Binder spraying system	2.5
		Total amount of	100.00

The anionic agglomerate 1 contains 40% anionic surfactant, 27% zeolite and 33% carbonate.

The anionic agglomerate 2 contains 40% anionic surfactant, 28% zeolite and 32% carbonate.

The cationic agglomerates contained 20% cationic surfactant, 56% zeolite and 24% sulfate.

The layered silicate contains 95% SKS6 and 5% silicate.

The bleach activator agglomerate contains 81% TAED, 17% acrylic acid/maleic acid copolymer (acid form) and 2% water.

The ethylenediamine N, N-disuccinate/sulfate particles contained 58% ethylenediamine N, N-disuccinate, 23% sulfate and 19% water.

The encapsulated sulfonated zinc phthalocyanine was 10% active.

The suds suppressor contained 11.5% silicone oil (from Dow Corning), 59% zeolite, and 29.5% water.

The binder spraying system contains 50 percent of Lutensit K-HD96And 50% PEG (polyethylene glycol).

	Composition C (％)
		Anionic agglomerates 1	9.1
Anionic agglomerates 2	22.5
		Nonionic agglomerates	9.1
Cationic agglomerates	4.6
		Layered silicate	9.7
Sodium percarbonate	12.2
		Bleach activator agglomerates	6.1
Sodium carbonate	7.27
		EDDS/sulfate particles	0.5
Hydroxy ethane diphosphonic acid tetrasodium salt	0.6
		Soil release polymers	0.3
Fluorescent agent	0.2
		Encapsulated sulfonated zinc phthalocyanines	0.03
Soap powder	1.2
		Suds suppressor	2.8
Citric acid	5.5
		Protease enzyme	1
Lipase enzyme	0.35
		Cellulase enzymes	0.2
Amylase	1.1
		Binder spraying system	3.05
Spraying perfume	0.5
		DIBS	2.1

The anionic agglomerate 1 contains 40% anionic surfactant, 27% zeolite and 33% carbonate.

The anionic agglomerate 2 contains 40% anionic surfactant, 28% zeolite and 32% carbonate.

The nonionic agglomerates contained 26% nonionic surfactant, 6% lutenst K-HD96, 40% anhydrous sodium acetate, 20% carbonate, and 8% zeolite.

The cationic agglomerates contained 20% cationic surfactant, 56% zeolite and 24% sulfate.

The layered silicate contains 95% SKS6 and 5% silicate.

The bleach activator agglomerate contains 81% TAED, 17% acrylic acid/maleic acid copolymer (acid form) and 2% water.

The ethylenediamine N, N-disuccinate/sulfate particles contained 58% ethylenediamine N, N-disuccinate, 23% sulfate and 19% water.

The encapsulated sulfonated zinc phthalocyanine was 10% active.

The suds suppressor contained 11.5% silicone oil (from Dow Corning), 59% zeolite, and 29.5% water.

The binder spray system contained 0.5 parts Lutensit K-HD96 and 2.5 parts PEGs.

	Composition D (％)
		Anionic agglomerates 1	32
		Cationic agglomerates	5
Layered silicate	11.5
		Sodium percarbonate	16.2
Bleach activator agglomerates	4.7
		Sodium carbonate	3.76
Sodium bicarbonate	2.0
		Sodium sulfate	2.4
EDDS/sulfate particles	0.5
		Hydroxy ethane diphosphonic acid tetrasodium salt	0.8
Soil release polymers	0.3
		Fluorescent agent	0.1
Encapsulated sulfonated zinc phthalocyanines	0.02
Suds suppressor	2.1
		Citric acid	2
Protease enzyme	0.7
		Lipase enzyme	0.2
Cellulase enzymes	0.2
		Amylase	0.6
Encapsulated fragrance	0.2
		Polymer particles	3
Sprayed fragrance	0.35
		Nonionic spray system	5.17
Zeolite	6.2

The anionic agglomerate 1 contains 40% anionic surfactant, 27% zeolite and 33% carbonate.

The cationic agglomerates contained 20% cationic surfactant, 56% zeolite and 24% sulfate.

The layered silicate contains 95% SKS6 and 5% silicate.

The bleach activator agglomerate contains 81% TAED, 17% acrylic acid/maleic acid copolymer (acid form) and 2% water.

The ethylenediamine N, N-disuccinate/sulfate particles contained 58% ethylenediamine N, N-disuccinate, 23% sulfate and 19% water.

The encapsulated sulfonated zinc phthalocyanine was 10% active.

The suds suppressor contained 11.5% silicone oil (from Dow Corning), 59% zeolite, and 29.5% water.

The encapsulated perfume contained 50% perfume and 50% starch.

The polymer particles contained 36%, 54% zeolite and 10% water.

The nonionic spray system contained 67% C12-C15 AE5 (alcohol with an average of 5 ethoxy groups per molecule), 24% N-methylglucamide and 9% water.

Claims (10)

1. 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 the tablet has more than two layers, the tablet's less elastic layer is located at its ends.

2. A tablet according to claim 1, wherein the tablet composition comprises sodium diisoalkylbenzene sulphonate.

3. A tablet according to claim 1, wherein the less elastic layer contains a higher concentration (by weight) of surfactant.

4. A tablet according to claim 1, wherein the tablet has a less elastic layer at its ends.

5. A tablet according to claim 1, wherein the more elastic layer of the tablet is at its end.

6. A tablet according to claim 1 wherein the entire tablet contains at least 5% by weight of surfactant.

7. A tablet according to claim 1, said whole tablet having a density of at least 0.9g/cc, preferably less than 2 g/cc.

8. A tablet according to claim 1, wherein the tablet has a substantially square or rectangular cross-section.

9. A coated detergent tablet, wherein the non-coated tablet conforms to any of the preceding claims.

10. A process for the preparation of a detergent tablet according to the invention, wherein the higher elastic layer of the tablet is located at its bottom end during production.

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