CN1309696A - Process for producing powder from packaged tablet - Google Patents

Abstract

The present invention relates to a process for producing a powder from a packaged tablet, the package comprising plastic materials, whereby the process is characterised in that it comprises a first step of submitting the packaged tablet to mechanical degradation with first mechanical degradation means, a second step of sifting with first sifting means to obtain an intermediate material, a third step of submitting the intermediate material to mechanical degradation with second mechanical degradation means, and a fourth step of sifting with second sifting means to obtain the powder, whereby the powder obtained comprises less than 0.05 % per weight of plastic material.

Description

Method for preparing powder from packaging sheet

The present invention relates to a process for the preparation of a powder from packaged detergent tablets, particularly those suitable for washing.

Detergent tablets are widely used in different types of washing or cleaning applications. In automatic dishwashing applications, the tablets are made from a high-pressure powder of initially given chemical composition, whereby the high-pressure tablets are solid and therefore insensitive to mechanical stress, so that the tablets are easily dissolved in the dishwashing machine, resulting in an aqueous solution containing the surfactant. In the process of making such tablets, it may happen that a small proportion of the tablets produced are unsuitable for use, for example because of the absence of the appropriate chemical composition, or because of breakage on the production line. In this case, the tablets which are not suitable for use are generally recycled by crushing and dissolving them to form a solution, so that a powder can be produced from this solution, which is added to the original powder in a small proportion and then compressed into tablets which are suitable for use.

In the case of packaging tablets, the process becomes further complicated, whereby also powders can be prepared using such tablets, and it should be avoided that the powder obtained contains packaging pieces. The object of the present invention is to selectively separate the package from its contents, i.e. the tablet, avoiding the contamination of the powder produced by the residual package.

The present invention relates to a method for preparing a powder from a packaging sheet, said packaging comprising a plastic.

The advantage of this method is that it can be used to reduce environmental waste while maintaining satisfactory quality of the used tablets.

Despite these and other advantages, existing processes for preparing powders from tablets, particularly processes used for recycling automatic dishwashing tablets, have disadvantages. For example, in the case where the sheet is packaged and then processed, this method is not suitable for separating the package from the sheet.

The present invention seeks to provide a process of the above-mentioned kind which makes it possible to obtain recycled powders which are not contaminated by packaging residues.

Summary of The Invention

According to the invention, this object is achieved by a method of the above class, comprising a first step of: subjecting the packaging sheet to mechanical degradation using a first mechanical degradation device; the second step is as follows: screening by using first screening equipment to obtain an intermediate; the third step: subjecting the intermediate to mechanical degradation with a second mechanical degradation device, and a fourth step: sieving with a second sieving device to obtain a powder, whereby the powder obtained contains less than 0.05% by weight of plastic.

The process of the invention has various advantages. Since mechanical agitation and sieving are used to recycle the tablets, a recycled powder can be obtained without a dissolution step, but under special conditions, it may be preferable to add such a step. In addition, the combination of these four steps results in a powder with a minimum amount of plastic.

Detailed Description

The present invention relates to a process for preparing a powder from a packaged tablet. In a preferred embodiment of the invention the sheet has a tensile strength of at least 5kPa, preferably a tensile strength of at least 10kPa, more preferably at least 15kPa, even more preferably at least 20kPa, so that the sheet is sufficiently resistant to mechanical forces while being easily dissolvable. The tablet also preferably contains a surfactant, more preferably at least 2% by weight surfactant. In a preferred embodiment of the invention, the tablet comprises at least 10% by weight surfactant, more preferably at least 15%, most preferably at least 20%. In fact, the present invention more particularly relates to laundry tablets, laundry tablets having a particularly high level of surfactant. The method of the present invention comprises a first step whereby the tablet is subjected to mechanical degradation. The mechanical degradation can be achieved by different means, the preferred mechanical degradation means being provided by centrifugation, preferably using a centrifugal screen, in particular a KEK centrifugal screen available from KEMUTEC, preferably K650. The second step of the process consists of sieving, yielding an intermediate. In fact, after being subjected to mechanical degradation, the packaging sheet is not a solid block but consists of a large number of particles or packaging pieces. Sieving may select a portion of these particles or packaging fragments. In a preferred embodiment of the invention, the sieving in the second step is performed by a mesh having a large number of holes with a diameter of 8 mm. Preferably, the mesh size is 2 to 15mm, more preferably 5 to 12mm, most preferably 6 to 10 mm. The remaining particles or packaging fragments that have not been sieved are discarded and are not included in the intermediate. Typically, the remaining pellets or packaging pieces not subjected to the second step comprise less than 1% by weight of the total pellets or packaging pieces. Most of this remainder is made of plastic. Preferably, this remainder is not reintroduced directly into the initial phase of the process of the invention, but may be subjected to additional treatments. According to the invention, the intermediate is then subjected to a third step, similar to the first step, and to a fourth step, similar to the second step. For the fourth step, it is preferred to use a nylon sieve with pore sizes between 2.4 and 3.5mm in diameter. Preferably, the mesh size or pore diameter is between 1 and 6mm, more preferably between 1.5 and 5mm, most preferably between 2 and 4 mm. Similarly, some of the intermediate was screened and others were discarded. According to the invention it has been found that using this method a powder can be obtained comprising less than 0.05% by weight of plastic, preferably less than 0.03% by weight, more preferably less than 0.02%, most preferably less than 0.01%.

In a preferred embodiment of the invention, the intermediate is such that it contains less than 5% by weight of particles passing through a 150 micron sieve and the resulting powder is such that it contains less than 6% by weight of particles passing through a 150 micron sieve. In a preferred embodiment, the resulting powder is one that contains less than 5% by weight of particles passing through a 150 micron sieve. It should be appreciated that the 150 micron sieve referred to is generally different from the sieving equipment used in the second step of the present invention, which 150 micron sieve is mentioned above for the purpose of providing equipment for analysing the granular structure of the resulting powder or intermediate. The minimum content of fine particles improves the cleaning and environmental properties of the resulting powder. This applies more particularly to tablets containing enzymes, whereby it is preferred that the enzyme component of the tablet does not break during processing. Breakage of the percarbonate component should also be avoided, as the stability of the finished product may be affected. In fact, the sheets of the invention are generally sheets that need to be packaged in order to stabilize their chemical evolution of gases due to the specific nature of the packaging, as described in EP application 97202674.4. Indeed, in a preferred embodiment, the invention relates to percarbonate containing tablets. In addition, if the tablets are made to contain the powder produced, the level of fine particles is limited to provide better dissolution of the tablets in the wash environment.

The invention is particularly useful for remixing unsatisfactory tablets into a base powder, whereby the resulting powder is added to the base powder to form a mixture, the added powder comprising at least 1% by weight up to 20% by weight of the mixture, the mixture being compressed into tablets. Preferably, in this case, the powder obtained comprises a percentage by weight of particles passing through the 150 micron sieve which is lower than 2 times the percentage by weight of particles contained in the raw powder and passing through the 150 micron sieve. In fact, the more the powder obtained has a grain structure close to that of the original powder, in particular considering the fine grains, the more reliable this method of remixing is. In this case, the tablets themselves subjected to the process of the invention are generally prepared by pressing raw powders, and by adding or not adding film-forming agents. In general, the present invention relates to sheets having a tensile strength of less than 700 kPa. More preferred are sheets having a tensile strength of less than 150kPa, even more preferred are sheets having a tensile strength of less than 100kPa, and most preferred are sheets having a tensile strength of less than 50kPa or even less than 30 kPa. In fact, the tablets of the present invention should be readily soluble in the wash environment so the tablets should not be compressed excessively. It is noted that the process according to the invention is also believed to enable the preparation of powders from tablets for general automatic dishwashing, but the dissolution characteristics are less stringent than for laundry tablets, so that the invention is even more advantageous when applied to laundry tablets.

When used industrially, the process of the invention makes it possible to process a large number of tablets at a speed of at least 100kg, up to 300 kg/h, per mechanical degradation and screening apparatus.

Packaging of tablets

In a preferred embodiment, the tablet of the invention comprises a bleaching agent. Typically, the bleaching agent is an inorganic perhydrate bleach. Such bleaching agents include sodium perborate, which may be in the monohydrate or tetrahydrate form. Other perhydrate salts may also be used, for example sodium percarbonate. This component is a suitable source of carbonate ions for cleaning purposes. However, such percarbonates are particularly unstable in humid environments and also release gases, such as oxygen. Thus, the packaging should be suitable in view of these two features.

Since the bleach decomposes in moisture and thus loses its bleaching properties, it is important to avoid the sheet from getting moisture on the outside. Ideally, this is achieved by packaging each sheet in a separate package, opened just prior to use, which is completely water impermeable. To obtain effective protection for the sheet, it is preferred that the packaging system have a limited Moisture Vapor Transfer Rate (MVTR). The MVTR of the packaging system is determined at 40 ℃ and 75% ehr, which corresponds to a damage to the sheet, in particular in terms of the environment. It was found that the MVTR should not exceed 20g/m²Day in order to meet the requirements of the packaging system, corresponding to an effective protection for 6 months under real conditions.

The packaging system should also take into account the fact that gas may be released from its contents. This can be achieved by making micro-holes in the packaging system. The micro-holes serve to communicate the interior of the packaging system with the exterior. The main property of the pores is that the provided interaction is sensitive to pressure. In fact, if the internal and external pressures of the packaging system are in equilibrium, the micro-pores have a negligible effect on the transmission properties of the packaging system due to the resiliency of the material. In fact, when making the micro-holes, no substantial amount of material is lost, so it is essentially enclosed in a bag where no pressure gradient exists inside and outside. However, once a pressure gradient occurs, the packaging system will be slightly distorted so that the micro-holes will open themselves, allowing effective communication between the exterior and the interior of the package to minimize the pressure gradient. This means that in case of a released gas the internal pressure will rise and the resulting pressure gradient will open pores through which excess gas is discharged. The pores act as vents and do not allow moisture to enter the bag in a significant manner, since the external pressure is usually always lower than or equal to the internal pressure. The mechanism can be coordinated by the use of various sizes of micro-apertures and by the selection of the number of micro-apertures required for each packaging system, taking into account the composition and amount of the contents of the packaging system, and also taking into account the MVTR of the packaging system. In fact, a non-zero MVTR may allow some intercommunication between the interior and exterior of the pouch.

The packaging system of the preferred embodiment initially consists of a sheet (2) having the desired MVTR. Materials suitable for such use include monolayer, coextruded or laminated films. Such films may include various components such as polyethylene, polypropylene, polystyrene, polyethylene terephthalate. In the most preferred embodiment of the invention, the packaging system is comprised of a co-extruded film of polyethylene and bi-directional polypropylene having an MVTR of less than 1 g/day/m². The MVTR of the packaging system is preferably less than 10 g/day/m²More preferably less than 5 g/day/m²Even more preferably less than 1 g/day/m²Most preferably less than 0.5 g/day/m². The film (2) may have various thicknesses. The thickness should generally be in the range of from 10 to 150. mu.m, preferably from 15 to 120. mu.m, more preferably from 20 to 100. mu.m, even more preferably from 25 to 80 μm,most preferably 30-40 μm.

Highly soluble compounds

The tablets according to the invention may further comprise highly soluble compounds to further facilitate dissolution. Such compounds may be prepared from mixtures or from a single compound. Highly soluble compounds are defined as follows:

a solution containing deionized water and 20g of the specified compound per liter was prepared as follows:

1-20 g of the particular compound were placed in a Sotax beaker. The beaker was placed in a constant temperature bath fixed at 10 ℃. The stirrer with marine propeller was placed in the beaker with the bottom of the stirrer 5mm above the bottom of the Sotax beaker. The rotational speed of the mixer was fixed at 200 revolutions per minute.

2-980 g of deionized water was added to the Sotax beaker.

3-the conductivity of the solution was measured using a conductivity meter 10 seconds after the water injection.

4-repeat step 3 after 20, 30, 40, 50 seconds, 1 minute, 2 minutes, 5 minutes and 10 minutes after step 2.

5-the measurement taken at 10 minutes was taken as the plateau or maximum.

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 time when the deionized water is added to the compound. In fact, when the conductivity is monitored in this way, the conductivity levels off after a period of time, this plateau value being considered as the maximum value. This compound is preferably in the form of a flowable material consisting of solid particles which are easy to handle at 10-80 ℃, but other forms may be used, such as a paste or liquid.

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

Bonding action

The tablet according to the invention may also comprise a compound or a mixture of compounds having a binding effect, so that the tablet is even more mechanically strong under constant pressure. The binding action on the granular material of the detergent matrix is characterized by the force required to break up the tablets, which are based on the detergent matrix tested being pressed under controlled pressure conditions. For a given pressure, a high strength of the sheet means that the particles are highly bonded together when pressed, so a strong bonding action occurs. The method of assessing tablet strength (also known as radial rupture stress) is described in Pharmaceutical dosage forms (Pharmaceutical dosage forms): tablets, volume 1, editor h.a. lieberman et al, published in 1989.

The cohesion effect produced by the highly soluble compound is determined according to the invention by comparing the tablet strength of the raw base powder without the highly soluble compound with the tablet strength of a powder mixture comprising 97 parts of raw base powder and 3 parts of highly soluble compound. The highly soluble compound is added to the matrix in a substantially anhydrous form (water content below 10% (preferably below 5%)). The temperature of addition is 10-80 deg.C, more preferably 10-40 deg.C.

A highly soluble compound is defined as having a binding effect on the particulate material of the invention, and when a tablet weighing 50g of detergent particulate material and having a diameter of 55mm is provided at a given pressure of 3000N, the tablet tensile strength is increased by more than 30% (preferably 60%, more preferably 100%) in the presence of 3% of a highly soluble compound having a binding effect on the base particles.

It has been observed that the dissolution of tablets in aqueous solution is significantly increased, especially when combined with highly soluble compounds having a binding effect on tablets formed by compressing particulate material comprising surfactant. In a preferred embodiment at least 1% by weight of the tablet is constituted by the highly soluble compound, more preferably at least 2%, even more preferably at least 3%, most preferably at least 5% by weight of the tablet is constituted by the highly soluble compound having a binding effect on the particulate material.

It is noted that compositions comprising highly soluble compounds and surfactants are disclosed in EP-A-524075, which compositions are liquid compositions.

The highly soluble compound having a binding effect on the particulate material enables tablets having higher tensile strength to be obtained at a constant pressure or equivalent tensile strength to be obtained at a lower pressure when compared with conventional tablets. Generally, the sheet has a tensile strength of greater than 5kPa, preferably greater than 10kPa, more preferably, particularly for use in laundry applications, greater than 15kPa, even more preferably greater than 30 kPa; the tensile strength is below 100kPa, even more preferably below 80kPa, most preferably below 60 kPa. In fact, in laundry applications, the compressed tablet should be slightly weaker than in, for example, automatic dishwashing applications, and thus more soluble, so that in laundry applications, the tensile strength is most preferably below 30 kPa.

This enables the robustness and mechanical resistance of the tablets to be made which is comparable to that of conventional tablets, whilst the tablets are low-compressed and therefore more readily soluble. In addition, since the compound is highly soluble, dissolution of the tablet is also promoted, resulting in a synergistic effect that promotes dissolution of the tablet of the present invention.

Preparation of tablets

The present invention enables low compression and low compaction of the tablet to be obtained at constant pressure when compared to conventional detergent tablets.

The detergent tablets of the invention may be prepared simply by mixing the solid components together and compressing the mixture using a conventional tablet press as used in the pharmaceutical industry, for example. Preferably, the major component, especially the gelling surfactant, is used in particulate form. Any liquid component, such as a surfactant or suds suppressor, can be incorporated into the solid particulate component in a conventional manner.

In particular for laundry tablets, ingredients such as builders and surfactants can be spray-dried by conventional methods and then compressed at appropriate pressures. Preferably, the tablets of the invention are compressed with a force of less than 100000N, more preferably less than 50000N, even more preferably less than 5000N, most preferably less than 3000N. In fact, the most preferred embodiment is tablets pressed with a force below 2500N suitable for laundry, but for example tablets for automatic dishwashing are also contemplated whereby such automatic dishwashing tablets are typically pressed more strongly than laundry tablets.

The particulate material used to make the tablets of the present invention may be prepared by any granulation or prilling method. An example of such a process is spray drying (in co-current or counter-current spray drying towers), which generally results in a low bulk density of 600g/l or less. By granulation and densification 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) can produce higher density particulate materials. Other suitable processes include fluidized bed processes, compression processes (e.g., roller compression), extrusion, and the preparation of any particulate material by chemical processes such as flocculation, crystallization, and the like. The particles may also be any other particulate, granular, prill or granule.

The components of the particulate material may be mixed together using any conventional apparatus, and a batch process is suitable, for example, for a concrete mixer, Nauta mixer, ribbon mixer or any other apparatus. Alternatively, the mixing process may be carried out continuously by metering the weight of the components onto a moving belt and mixing them by stirring in one or more drums or mixers. A non-gelling binder may be sprayed onto some or all of the mixture of particulate material components. Other liquid components may also be sprayed onto the mixture of the individual or premixed components. For example, perfume and optical brightener slurries can be sprayed. Preferably, near the end of the process, the binder is sprayed to make the mixture low-viscous, after which finely divided flow aids (release agents such as zeolites, carbonates, silicas) are added to the particulate material.

Can use any pressureThe process of the type(s) produces tablets, such as tablets, briquettes or extrusions, preferably tablets. Suitable equipment includes standard single stroke or rolling presses (e.g., Courtoy)^®,Korch^®,Manesty^®Or Bonals^®). The tablets prepared according to the invention preferably have a diameter of 20mm to 60mm, preferably at least 35 and up to 55mm, and a weight of between 25 and 100 g. The ratio of the height to the diameter (or width) of the tablet is preferably greater than 1: 3, more preferably greater than 1: 2. The pressure used for preparing the tablets should not exceed 100000kN/m²Preferably not more than 30000kN/m²More preferably not more than 5000kN/m²And even more preferably not more than 3000kN/m²Most preferably not more than 1000kN/m². In a preferred embodiment of the invention, the tablets have a density of at least0.9g/cc, more preferably at least 1.0g/cc, preferably less than 2.0g/cc, more preferably less than 1.5 g/cc.

Hydrotrope compounds

In a preferred embodiment of the invention, the tablet further comprises a hydrotrope compound which further facilitates dissolution of the tablet in aqueous solution, a particular compound being a hydrotrope as defined below (see s.e. friberg and m.chiu, journal of dispersion science and Technology, 9(5&6), p. 443-457 (1988-1989)):

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

2. Octanoic acid was then added to the solution at a temperature of 20 c at 1.6 times the weight of the particular compound in the solution. The solution was mixed in a Sotax beaker with a stirrer with a marine propeller located approximately 5mm above the bottom of the beaker, the speed of the mixer was fixed at 200 revolutions per minute.

3. If the octanoic acid is completely dissolved, i.e. if the solution comprises only one phase, which is a liquid phase, the specific compound is a hydrotrope.

It is noted that in a preferred embodiment of the invention, the hydrotrope compound is a material made from solid particles that is flowable at operating conditions of 15-60 ℃.

Hydrotrope compounds include the compounds listed below:

a list of commercially available hydrotropes can be found in the emulsifier and detergent of McCutcheon, published by the McCutcheon division of candy making companies (Manufacturing conditioners Company). Useful compounds also include:

1. a nonionic hydrotrope having the structure: R-O- (CH)₂CH₂O)_x(CH-CH₂O),H

｜

CH₃

Wherein R is C₈-C₁₀An alkyl chain, x is in the range of 1 to 15 and y is 3 to 10.

2. Anionic hydrotropes such as alkali metal aryl sulphonates. This includes alkali metal benzoates, salicylates, benzenesulfonates and many of their derivatives, naphthoates, and various hydroaromatics. Examples of these are sodium, potassium and ammonium benzenesulfonates derived from toluenesulfonic acid, xylenesulfonic acid, isopropylbenzenesulfonic acid, tetrahydronaphthalenesulfonic acid, naphthalenesulfonic acid, methylnaphthalenesulfonic acid, dimethylnaphthalenesulfonic acid, trimethylnaphthalenesulfonic acid.

Other examples include dialkyl benzene sulfonates such as diisopropylbenzene sulfonate, ethylmethyl benzene sulfonate, alkylbenzene sulfonates having an alkyl chain length of 3 to 10 (preferably 4 to 9) carbon atoms, and straight or branched alkyl sulfonates having an alkyl chain of 1 to 18 carbon atoms.

3. Solvent hydrotropes such as alkoxylated glycerol and alkoxylated glycerides, ester alkoxylated glycerol, alkoxylated fatty acids, glycerides, polyglycerides. Preferred alkoxylated glycerols have the following structure:

wherein 1, m and n are each a number from 0 to about 20, 1+ m + n = about 2 to about 60, preferably about 10 to about 45, and R represents H, CH₃Or C₂H₅。

Preferred alkoxylated glycerides have the following structure:

wherein R1 and R2 are each C_nCOO or- (CH)₂CHR₃-O)₁-H, wherein R₃=H、CH₃Or C₂H₅1 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, wherein,

r is H or C₁-C₁₀Alkyl or a hydrophilic functional group;

r1 is H or lower alkyl or aryl;

r2 is H or cycloalkyl or aryl.

The polymer typically has a molecular weight of about 1000-.

5. Hydrotropes of unconventional structure, for example 5-carboxy-4-hexyl-2-cyclohexen-1-yl octanoic acid (Diacid).

The use of such compounds in the present invention further increases the dissolution rate of the tablet because the hydrotrope compound facilitates the dissolution of, for example, surfactants. Such compounds may be prepared from mixtures or from single compounds.

Coating layer

By preparing the coated tablets, the robustness of the tablets of the invention is further improved, the coating covering the uncoated tablets of the invention, thereby further improving the mechanical properties of the tablets while maintaining or further improving dissolution.

In one embodiment of the invention, the sheet may then be coated so that the sheet does not absorb water or only absorbs water at a very slow rate. The coating is also strong such that the tablets are subjected to moderate mechanical impact during use, packaging and shipping resulting in no more than a very low amount of breakage or wear. Finally, the coating is preferably frangible so that the sheet breaks when subjected to strong mechanical impact. In addition, it is advantageous if the coating material dissolves under alkaline conditions or is easily emulsified by surfactants. This helps to avoid the problem of visible residues adhering to the window of the front-loading washing machine during the washing phase and also to avoid undissolved particles or lumps of coating material being deposited on the washed load.

Water solubility was determined using the following ASTM E1148-87, test protocol entitled "Standard test methods for determining Water solubility".

Suitable coating materials are dicarboxylic acids. Particularly suitable dicarboxylic acids are selected from 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.

The coating material has a melting point preferably in the range of 40 ℃ to 200 ℃.

The coating may be applied in a variety 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 and cured on the sheet at a temperature above its melting point. In b), the coating material is applied as a solution and the solvent is dried, leaving a coherent coating. The substantially insoluble material may be applied to the sheet by, for example, spraying or dipping. Typically, when the molten material is sprayed onto the sheet, it quickly solidifies to form an adherent coating. Rapid solidification of the coating material can be caused when the sheet is dipped into the molten material, then removed, and rapidly cooled. It is clear that substantially insoluble materials having a melting point below 40 c are not sufficiently curable at room temperature and that materials having a melting point above about 200 c have not been found to be practical. Preferably, the melting point of the material is between 60 ℃ and 160 ℃, more preferably between 70 ℃ and 120 ℃.

By "melting point" is meant the temperature at which the material becomes a transparent liquid when heated slowly in, for example, a capillary.

Any desired thickness of the coating may be applied according to the present invention. For most purposes, the coating will comprise from 1% to 10%, preferably from 1.5% to 5% by weight of the tablet.

The tablet coating of the present invention is very hard and provides an ultra-strength to the tablet.

In a preferred embodiment of the invention, the cracking of the coating in the wash is improved by the addition of a disintegrant to the coating. The disintegrant swells upon contact with water and breaks the coating into small pieces. This will improve the dissolution of the coating in the wash solution. The amount of disintegrant suspended in the coating melt is up to 30%, preferably 5% to 20%, most preferably 5% to 10% by weight. Possible disintegrants are described in the handbook of pharmaceutical excipients (1986). Examples of suitable disintegrants include starch; native, modified or pregelatinized starches; sodium starch gluconate; a gum; agar; guar gum; locust bean gum; karaya gum; pectin; gum tragacanth; croscarmylose sodium, crospovidone, cellulose, carboxymethylcellulose, alginic acid and salts thereof, including sodium alginate, silica, clays, polyvinylpyrrolidone, soybean polysaccharides, ion exchange resins, and mixtures thereof.

Tensile strength

Depending on the composition of the raw material and the shape of the tablet, the pressure used can be adjusted without affecting the tensile strength and the disintegration time in the washing machine. The process can be used to prepare uniform or layered tablets of any size or shape.

For cylindrical sheets, tensile strength is equivalent to radial fracture stress (DFS), which is one way to express sheet strength, determined by the following equation:

=2F

πDt

measured with a VK 200-piece hardness tester supplied by Van Kell industries, inc, where F is the maximum force (newtons) that causes loss of tension (cracking). D is the diameter of the sheet and t is the thickness of the sheet. (pharmaceutical dosage form: tablet, Vol.2, p.213-217).

Sheets having a radial rupture stress below 20kPa are considered brittle and may result in some breakage of the sheet to the consumer. Preferably the radial rupture stress is at least 25 kPa. In general, the sheets of the present invention have a tensile strength in the direction perpendicular to the major axis of greater than 5kPa, preferably greater than 10kPa, more preferably, especially for laundry applications, greater than 15kPa, even more preferably greater than 20 kPa. The tablets of the invention should also be readily soluble so that the tensile strength is preferably less than 75kPa, more preferably less than 50 kPa.

The same applies to non-cylindrical sheets to determine tensile strength whereby the cross-section perpendicular to the height of the sheet is not circular and whereby forces are applied in a direction perpendicular to the height of the sheet and perpendicular to the side of the sheet that is perpendicular to the non-circular cross-section.

Feeding of tablets

The feed rate of the detergent tablet can be determined as follows:

two pieces, each nominally 50g, were weighed into the feeder of a Baucknecht WA9850 washer. The water temperature to the washer was fixed at 20 c, the hardness at 21 grains/gallon, and the inlet water flow rate to the feeder was fixed at 8 liters/minute. The power to the washing machine was switched on and the wash cycle was set to wash program 4 (white/color, short cycle), checking the amount of residual pieces remaining in the feeder. The percentage of feed was determined as follows:

% feed = residue weight x 100/base tablet weight

This procedure was repeated 10 times to determine the residue content and the average residue content was calculated from the 10 individual measurements. In this stress test, a residue of 40% by weight of the starting sheet was considered acceptable. Preferably less than 30% residue, more preferably less than 25%.

It is noted that the measure of water hardness is given in the traditional "grains/gallon" unit, whereby 0.001 mol/liter =7.0 grains/gallon, representing Ca²⁺Concentration of ions in solution.

Foaming agent

In another preferred embodiment of the invention, the tablet further comprises a foaming agent, which is a compound that facilitates dissolution of the tablet in an aqueous solution.

Foaming, as defined herein, means that carbon dioxide gas is generated as a result of a chemical reaction between a soluble acid source and an alkali metal carbonate, resulting in gaseous bubbles emanating from the liquid,

namely:

i.e.

additional examples of acid and carbonate sources and other blowing agent systems can be found in: (pharmaceutical dosage form: tablet, Vol.1, p.287-291).

In addition to the detergent component, a sudsing agent may be added to the tablet mixture. The addition of sudsing agents to detergent tablets improves the disintegration time of the tablets. Preferably in an amount of from 5% to 20%, most preferably from 10% to 20% by weight of the tablet. Preferably, the blowing agent should be added as an agglomerate of different particles or as a compact, rather than as a separate particle.

Because the effervescent agent in the tablet generates gas, the tablet may have a higher d.f.s. but still have the same disintegration time as a tablet without effervescent agent. The tablets with blowing agent decomposed faster when the d.f.s. of the tablets with blowing agent remained the same as the tablets without blowing agent.

Additional dissolution aids may be provided by the use of compounds such as sodium acetate or urea. A list of suitable dissolution aids can also be found in pharmaceutical dosage forms: tablets, volume 1, version 2, coded by H.A. Lieberman et al, ISBN 0-8247-8044-2.

Detersive surfactant

Surfactants are included in the tablets of the present invention. By adding a highly soluble compound, the dissolution of the surfactant is facilitated.

Non-limiting examples of surfactants suitable for use in the present invention-typically in amounts of about 1% to about 55% by weight, include conventional C₁₁-C₁₈Alkyl benzene sulfonates ("LAS"), and branched primary and random C₁₀-C₂₀Alkyl sulfates ("AS"), formula CH₃(CH₂)_x(CHOSO₃ ^-M⁺)CH₃And CH₃(CH₂)_y(CHOSO₃ ^-M⁺)CH₂CH₃C of (A)₁₀-C₁₈Secondary (2,3) alkyl sulfates wherein x and (y +1) are integers of at least about 7, preferably at least about 9, M is a water-soluble cation, particularly sodium, an unsaturated sulfate such as oleyl sulfate, C₁₀-C₁₈Alkyl alkoxy sulfates (' AE)_xS "; in particular EO1-7 ethoxy sulfate), C₁₀-C₁₈Alkyl alkoxy carboxylates (especially EO1-5 ethoxy carboxylates), C₁₀-C₁₈Glycerol ethers, C₁₀-C₁₈Alkyl polyglycosides and their corresponding sulfated polyglycosides, and C₁₂-C₁₈a-sulfonated fatty acid esters. If desired, conventional nonionic and amphoteric surfactants such as C may also be included in the overall compositions of the invention₁₂-C₁₈Alkyl ethoxylates ("AE") including so-called narrow peak alkyl ethoxylates and C₆-C₁₂Alkylphenol alkoxylates (in particular ethoxylates and mixed ethoxy/propoxylates), C₁₂-C₁₈Betaines and sulfobetaines, C₁₀-C₁₈Amine oxides, and the like. Also usable are C₁₀-C₁₈N-alkyl polyhydroxy fatty acid amides, typical examples include C₁₂-C₁₈N-methylglucamide. See WO9,206,154. Other saccharide-derived surfactants include N-alkoxy polyhydroxy fatty acid amides, e.g. C₁₀-C₁₈N- (3-methoxypropyl) glucamide. When low foaming is desired, N-propyl to N-hexyl C may be used₁₂-C₁₈A glucamide. Also usable are C₁₀-C₂₀Conventional soaps. If high foaming is desired, it is possible to use branches C₁₀-C₁₆Soap. Mixtures of anionic and nonionic surfactants are particularly useful. Other conventionally useful surfactants are listed in standard textbooks. In a preferred embodiment, the tablet comprises at least 5 wt% surfactant, more preferably at least 15 wt%, even more preferably at least 25 wt%, most preferably from 35% to 45 wt% surfactant.

Non-gelling binders

To further facilitate dissolution, a non-gelling binder may also be incorporated into the granules, making into tablets. Such compounds also facilitate dissolution of the tablet in aqueous solution.

If a non-gelling binder is used, suitable non-gelling binders include synthetic organic polymers such as polyethylene glycol, polyvinylpyrrolidone, polyacrylates, and water-soluble polyacrylate copolymers. The pharmaceutical excipients handbook, second edition, lists the following types of binders: gum arabic, alginic acid, carboxyvinyl polymer (Carbomer), sodium carboxymethylcellulose, dextrin, ethylcellulose, gelatin, guar gum, hydrogenated vegetable oil type 1, hydroxyethyl cellulose, hydroxypropyl methylcellulose, liquid glucose, magnesium aluminum silicate, maltodextrin, methylcellulose, polyisobutylene esters, povidone, sodium alginate, starch, and zein. Most preferred binders also have a cleaning action active in laundry, for example cationic polymers, i.e. ethoxylated hexamethylene diamine quaternary ammonium compounds, dihexamethylene triamine or other substances such as pentamine, ethoxylated polyethylene amine, maleic acrylic polymers.

Preferably sprayed with a non-gelling binder material, whereby it has a suitable melting point below 90 c, preferably below 70 c, even more preferably below 50 c, so as not to destroy or degrade the other active components in the matrix. Most preferred are non-aqueous liquid binders (i.e., not in aqueous solution) which can be sprayed in molten form. However, they may also be solid adhesives which are incorporated into the matrix by dry addition, but which have adhesive properties in the sheet.

The non-gelling binder material is preferably used in an amount of from 0.1% to 15%, more preferably less than 5%, especially less than 2% by weight of the tablet if it is a non-laundry active.

The use of gelling binders, such as nonionic surfactants, in liquid or molten form is preferably avoided. Nonionic surfactants and other gelling binders are not excluded from the composition, but preferably they are processed into the detergent tablet as a component of the particulate material, rather than as a liquid. Builder

Detergent builders may optionally be included in the compositions of the present invention to assist in controlling mineral hardness. Inorganic and organic builders can be used. Builders are commonly used in compositions for laundering fabrics to aid in the removal of particulate soils.

The level of builder may vary over a wide range depending on the end use of the composition.

Inorganic or phosphorous containing builders include, but are not limited to: the following alkali metal, ammonium and alkanolammonium salts: polyphosphates (exemplified by tripolyphosphates, pyrophosphates, and glassy polymeric metaphosphates), phosphonates, phytates, silicates, carbonates (including bicarbonates and sesquicarbonates), sulfates, and aluminosilicates. However, non-phosphate builders are required in certain areas. Importantly, the efficacy of the compositions of the present invention is unexpectedly good even in the presence of so-called "weak" builders (as compared to phosphates), such as citrate, or in so-called "low built" ("builder deficiency") which can occur when zeolite or layered silicate builders are used.

Examples of silicate builders are alkali metal silicates, especially those having SiO₂∶Na₂Silicates and layered silicates having a ratio of O in the range of 1.6: 1 to 3.2: 1, such as the layered sodium silicate described in US patent US4664839 to h.p. rieck, granted 5/12 in 1987. NaSKS-6 is a trademark of layered crystalline silicates sold by Hoechst (generally abbreviated herein as "SKS-6"). Unlike zeolite builders, Na SKS-6 silicate buildersDoes not contain aluminum. NaSKS-6 is a compound having delta-Na₂SiO₅A layer silicate in a morphological form. They can be prepared by processes such as those described in DE-A-3417649 and DE-A-3742043. SKS-6 is a highly preferred layered silicate for use herein, but other layered silicates, such as those having the general formula NaMSi, can be used in the present invention_xO_2x+1·yH₂Layered silicates of O, where M is sodium or hydrogen, x has a value of 1.9 to 4, preferably 2, and y has a value of 0 to 20, preferably 0 various other layered silicates available from Hoechst include NaSKS-5, NaSKS-7, and NaSKS-11, in the form of α, β, and γ₂SiO₅(NaSKS-6 form) is most preferred for use herein. Other silicates are also useful, such as magnesium silicate, as a crispening agent for granule formulations, as a stabilizer for oxygen bleaches, and as a component of foam control systems.

Examples of carbonate builders are the alkaline earth and alkali metal carbonates of German patent application 2321001 published on 11/15/1973.

Aluminosilicate builders are useful in the present invention. Aluminosilicate builders are of primary importance in the most commonly marketed heavy-duty granular detergent compositions, and can also be an important builder component in liquid detergent formulations. Aluminosilicate builders include builders having the empirical formula:

M_z(zAlO₂)_y]·xH₂o wherein z and y are integers of at least 6, the molar ratio of z to y is in the range of 1.0 to about 0.5, and x is an integer of about 15 to about 264.

Useful aluminosilicate ion exchange materials are commercially available. These aluminosilicates may be of crystalline or amorphous structure and may be naturally occurring aluminosilicates or synthetically derived. A process for preparing aluminosilicate ion exchange materials is disclosed in U.S. Pat. No. 3,3985669 to Krummel et al, issued 10/12/1976. Preferred synthetic crystalline aluminosilicate ion exchange materials for use herein are commercially available under the registered trademarks zeolite a, zeolite p (b), zeolite MAP and zeolite X. In a particularly preferred embodiment, the crystalline aluminosilicate ion exchange material has the formula:

Na₁₂[(AlO₂)₁₂(SiOx)₁₂]·xH₂o wherein x is from about 20 to about 30, especially about 27. This material is referred to as zeolite a. Dehydrated zeolites (x =0-10) may also be used herein. The aluminosilicate preferably has a particle size of about 0.1 to 10 microns in diameter.

Organic detergent builders suitable for the purposes of the present invention include, but are not limited to: various polycarboxylate compounds. As used herein, "polycarboxylate" refers to a compound having a plurality of carboxylic acid groups, preferably at least 3 carboxylic acid 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 used in the form of a salt, alkali metal salts such as sodium, potassium and lithium or alkanolammonium salts are preferred.

A variety of useful materials are included in polycarboxylate builders. One important class of polycarboxylate builders includes the ether polycarboxylates, including oxydisuccinates, such as those disclosed in U.S. Pat. No. 4,7 to Berg, 1964, and U.S. Pat. No. 3,3128287 to Lamberti et al, 1972, 1,8. See also U.S. patent US4663071 to Bush et al entitled "TMS/TDS" builder on 5.5.1987. Suitable ether polycarboxylates also include cyclic compounds, particularly cycloaliphatic compounds, as described in US 3923679; US 3835163; US 4158635; those described in US4120874 and US 4102903.

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

Citrate builders, for example, citric acid and its water-soluble salts (especially the sodium salt) are polycarboxylate builders of particular importance in heavy-duty liquid detergent formulations because they are available from renewable resources and because of their biodegradability. Citrate salts may also be used in granular compositions, particularly in combination with zeolite and/or layered silicate builders. Oxydisuccinates are also particularly useful in such compositions and mixtures.

Also suitable for use in the detergent compositions of the present invention are 3, 3-dicarboxy-4-oxa-1, 6-adipate salts and related compounds disclosed in U.S. patent number US4566984 to Bush, issued on 28.1.1986. Useful succinic acid builders include C₅-C₂₀Alkyl and alkenyl succinic acids and their salts. A particularly preferred compound of this type is dodecenylsuccinic acid. Specific examples of succinate builders include: lauryl succinate, myristyl succinate, palmityl succinate, 2-dodecenyl succinate (preferred), 2-pentadecenyl succinate, etc. Lauryl succinate is a preferred builder in this group and is described in European patent application 86200690.5/0200263 published on 5.11.1986.

Other suitable polycarboxylates are disclosed in U.S. Pat. No. 4,44226 to Crutchfield et al, granted on 3/13 1979, and U.S. Pat. No. 3308067 to Diehl, granted on 3/7 1967. See also U.S. Pat. No. 3,3723322 to Diehl.

Fatty acids, e.g. C₁₂-C₁₈Monocarboxylic acids may also be incorporated into the composition either alone or in combination with the aforementioned builders, especially citrate and/or succinate builders, to provide additional builder activity. The use of fatty acids generally results in impaired foaming, which the formulator should consider.

Where phosphorus-based builders can be used, especially in bar formulations for hand-washing operations, various alkali metal phosphates such as the well-known sodium tripolyphosphates, pyrophosphates and orthophosphates can be used. Phosphonate builders such as ethane-1-hydroxy-1, 1-diphosphonate and other well known phosphonates may also be used (see, for example, U.S. Pat. Nos. 3159581; 3213030; 3422021; 3400148 and 3422137).

Bleaching agent

The detergent compositions of the present invention may optionally contain a bleaching agent or a bleaching composition comprising a bleaching agent and one or more bleach activators. When present, bleaching agents are generally present at levels of from about 1% to 30%, more typically from about 5% to about 20% of the detergent composition, especially for laundering fabrics. If included, the bleach activator is typically present at a level of from about 0.1% to about 60%, more preferably from about 0.5% to about 40%, of the bleaching composition comprising the bleach and the bleach activator.

The bleaching agent used herein may be any bleaching agent suitable for use in detergent compositions for cleaning fabrics, cleaning hard surfaces, or other cleaning applications now known or to be known. These include oxygen bleaches as well as other bleaching agents. Perborate bleaching agents, such as sodium perborate (e.g., as a monohydrate or tetrahydrate), may be used herein.

Another class of bleaching agents that can be used without limitation includes percarboxylic acid bleaching agents and salts thereof. Suitable examples of such bleaches include magnesium monoperoxyphthalate hexahydrate, magnesium m-chloroperbenzoate, magnesium 4-nonylamino-4-oxoperoxybutyrate and magnesium diperoxydodecanedioate. These bleaches are disclosed in Hartman, U.S. patent No. US4483781,1985, issued 11/20 1984, Burns et al, U.S. patent application No. 3/6, 740446,1985, European patent application No. 0133354, issued on 20/2, Bank et al, and in Chung et al, U.S. patent No. US4412934, issued 11/1 1983. Highly preferred bleaching agents also include 6-nonylamino-6-oxo-peroxyhexanoic acid as described in U.S. patent No. 4,34551 to Burns et al, 6.1.7.

Peroxygen bleaching agents may also be used in the present invention. Suitable peroxy bleach compounds include sodium carbonate peroxyhydrate and its equivalents, "percarbonate" bleach, sodium pyrophosphate peroxyhydrate, urea peroxyhydrate, and sodium peroxide. Persulfate bleach (e.g., OXONE, commercially produced by dupont) may also be used.

Preferred percarbonate bleach compositions comprise dry particles having an average particle size in the range of from about 500 to about 1000 microns, no more than about 10% by weight of said particles being less than about 200 microns and no more than about 10% by weight of said particles being greater than about 1250 microns. The percarbonate may optionally be coated with silicate, borate or water soluble surfactants. Percarbonate is available from various suppliers such as FMC, Solvay and Tokai Denka.

Mixtures of bleaching agents may also be used.

Peroxygen bleaches, perborates, percarbonates, etc., are preferably used in combination with bleach activators, which result in the in situ generation of peroxyacids corresponding to the bleach activators in aqueous solution (i.e., during the wash). Various non-limiting examples of activators are disclosed in U.S. patent No. 4915854, and U.S. patent No. 4412934, issued to Mao et al at 4/10 1990. Nonoyloxybenzene sulfonate (NOBS) and Tetraacetylethylenediamine (TAED) activators are typical activators, and mixtures thereof may also be used. Other typical bleaching agents and activators useful herein are also described in US 4634551.

Highly preferred amido-derived bleach activators are those of 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 an alkylene radical having from 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 any group that is displaced from the bleach activator as a result of nucleophilic attack of the perhydrolytic anion on the bleach activator. A preferred leaving group is phenyl sulfonate.

Preferred examples of bleach activators of the above formula include (6-octanoylamino-hexanoyl) oxybenzene-sulfonate, (6-nonanoylamino hexanoyl) oxybenzene-sulfonate, (6-decanoylamino-hexanoyl) oxybenzene-sulfonate, and mixtures thereof, as described in U.S. patent No. 4634551, which is incorporated herein by reference.

Another class of bleach activators includes the benzoxazines disclosed in U.S. Pat. No. 4,4966723 to Hodge et al, granted at 30.10.1990 (which is incorporated herein by reference). Highly preferred activators of the benzoxazine class are:

another class of preferred bleach activators include acyl lactam activators, especially acyl caprolactams and acyl valerolactams of the formula:

wherein R is⁶Is H or an alkyl, aryl, alkoxyaryl, or alkylaryl group having from 1 to about 12 carbon atoms. Highly preferred lactam activators include benzoyl caprolactam, octanoyl caprolactam, 3,5, 5-trimethylhexanoyl caprolactam, nonanoyl caprolactam, decanoyl caprolactam, undecenoyl caprolactam, benzoyl valerolactam, octanoyl valerolactam, decanoyl valerolactam, undecenoyl valerolactam, nonanoyl valerolactam, 3,5, 5-trimethylhexanoyl valerolactam and mixtures thereof. See also U.S. Pat. No. 4,45784 to Sanderson, granted 10/8/1985, which is incorporated by reference herein in its entiretyIncorporated herein by reference, there are disclosed acyl caprolactams, including benzoyl caprolactam, which are adsorbed into sodium perborate.

Those bleaching agents other than oxygen bleaching agents are also well known in the art and may be used in the present invention. One particularly preferred class of non-oxygen bleaching agents includes photosensitizing bleaching agents such as sulfonated zinc and/or aluminum phthalocyanines. See US4033718 issued to Holcombe et al, 7/5 in 1977. If desired, detergent compositions will generally contain from about 0.025% to about 1.25% by weight of such bleaching agents, especially zinc phthalocyanine sulfonates.

If desired, the bleaching compound may be catalyzed by a manganese compound. Such compounds are well known in the art and include, for example, manganese-based catalysts as disclosed in US patents 5246621, US5244594, US5194416, US5114606 and european patent application publications EP549271Al, EP549272a1, EP544440a2 and EP544490a 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-III)Methyl-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-containing bleach catalysts include those disclosed in US4430243 and US 5114611. The use of manganese with various complex ligands for improving bleaching is also reported in the following U.S. patents: 4728455,5284944,5246612,5256779,5280117,5274147,5153161, and 5227084.

In practice, without limitation, the compositions and methods of the present invention may be adjusted to provide at least about one per million of active bleach catalyst in the aqueous wash solution, preferably from about 0.1ppm to about 700ppm, more preferably from about 1ppm to about 500ppm, of catalyst species in the wash solution.

Enzyme

Enzymes may be included in the formulations of the present invention for a variety of purposes in the laundering of fabrics, including, for example, the removal of protein, carbohydrate or triglyceride containing stains, and for the inhibition of dye migration by shedding, and for fabric restoration. Enzymes to be incorporated include proteases, amylases, lipases, cellulases, peroxidases, and mixtures thereof. Other types of enzymes may also be included. They may be obtained from any suitable source, for example plant, animal, bacterial, mould and yeast sources. However, their selection is governed by several factors, such as pH-activity and/or optimum stability, thermostability, and stability towards active detergents, builders, etc. In this respect, bacterial or fungal enzymes are preferred, such as bacterial amylases and proteases, and fungal cellulases.

Enzymes are generally incorporated in sufficient amounts to provide up to about 5 mg by weight, more typically from about 0.01 mg to about 3 mg of active enzyme per gram of detergent composition. In other words, the compositions of the present invention generally comprise from about 0.001% to about 5%, preferably from 0.01% to 1%, by weight of the commercial enzyme preparation. Proteases are typically present in such commercial preparations at levels sufficient to provide 0.005 to 0.1Anson Units (AU) of activity per gram of composition.

Examples of suitable proteases are subtilisins, which are obtained from particular strains of Bacillus subtilis and Bacillus licheniformis. Another suitable protease is obtained from a strain of Bacillus having maximum activity in the pH range 8-12, which has been developed and sold by the company Novo Industries A/S under the registered trade name ESPERASE. The preparation of this and similar enzymes is described in British patent specification GBl243784 to Novo corporation. Commercially available proteolytic enzymes suitable for removal of proteinaceous soils include those sold under the trade names ALCALASE and SAVINASE by Novo Industries A/S (Denmark) and MAXATASE by International Bio-Synthesis, Inc. (the Netherlands). Other proteases include protease A (see European patent application 130756 published on 9.1.1985); protease B (see European patent application No. 87303761.8, filed on 28.4.1987 and European patent application No. 130756, published on 9.1.1985 by Bott et al).

Amylases include, for example, α -amylase as described in UK patent specification 1296839(Novo), RAPIDASE from International biosynthetic Co., and TERMAMYL from Novo Industries.

Cellulases useful in the present invention include bacterial or fungal cellulases. Preferably, they have an optimum pH of 5 to 9.5. Suitable cellulases are disclosed in U.S. patent No. 4435307 issued on 3/6/1984 to Barbesgoard et al, which discloses cellulase derived from a mold produced by humicola insolens or humicola strain DSMl800 or a mold belonging to the genus aeromonas 212, and cellulase extracted from the hepatopancreas of marine mollusks (dolabella auricula Solander). Suitable cellulases are also disclosed in GB-A-2075028; GB-A-2095275 and DE-OS-2247832. CAREZYME (Novo) is particularly useful.

Suitable lipases which may be used in detergents include those produced by microorganisms of the Pseudomonas family, such as Pseudomonas stutzeri ATCC19.154, as disclosed in British patent 1372034. See also the lipase of Japanese patent application 5320487, published for public inspection on 24.2.1978. This lipase is available from Tianye Pharmaceutical Co., Ltd, Japan, and is known under the trade name Lipase P "Amano", hereinafter referred to as "Amano-P". Other commercially available lipases include Amano-CES, a lipase derived from Chromobacterium viscosum, e.g., Chromobacterium viscosum NRRLB 3673, available from Toyo Jozo Co., Tagata, Japan; there are also the Chromobacterium viscosum lipases from Biochemical Corp, USA and Disoynth in the Netherlands, and lipases from Pseudomonas gladioli. Lipase derived from Humicola lanuginosa (Humicola lanuginosa) and preferably used herein is the LIPOLASE enzyme commercially available from Novo (see also EPO 341947).

Peroxidases are used in combination with oxygen sources, e.g., percarbonates, perborates, persulfates, hydrogen peroxide, etc., for "solution bleaching," i.e., to prevent dyes or pigments that are released from a substrate during a washing operation from migrating to other substrates in the wash solution. Peroxidases are known in the art and include, for example, horseradish peroxidase, ligninase, and haloperoxidase such as chloro-or bromo-peroxidase. Detergent compositions containing peroxidase are disclosed in, for example, PCT International application WO89/099813 to O.Kirk, published 10/19 1989, assigned to Novo Industries A/S.

Various enzymatic materials and methods for their incorporation into synthetic detergent compositions are also disclosed in U.S. patent No. US3553139 to McCarty et al, issued on 5.1.1971. Enzymes are also disclosed in Place et al, US4101457, issued on 7/18 1978, and in Hughes, US4507219, issued on 3/26 1985. Enzymatic materials for liquid detergent formulations and methods for their incorporation into these formulations are disclosed in US4261868 to Hora et al, issued 4/14 in 1981. Enzymes used in detergents can be stabilized using a variety of techniques. Techniques for stabilizing enzymes are disclosed and exemplified in U.S. Pat. No. US3600319 issued to Gedge et al, 8/17 1971, and in European patent application publication No. 0199405, application No. 86200586.5 to Venegas, 10/29 1986. Enzyme stabilization systems are also described, for example, in US patent No. US 3519570.

Other components commonly used in detergent compositions and which may be incorporated in the detergent tablets of the invention include sequestrants, soil release agents, soil antiredeposition agents, dispersants, brighteners, suds suppressors, fabric softeners, dye transfer inhibitors and perfumes.

Examples

The following process is carried out according to the invention:

using the film packaging process, two flow-wrap sheets are placed in the film. In fact, in a preferred embodiment of the invention, the packaging sheet comprises at least 1.5% by weight of plastic, more preferably at least 2% by weight, and less than 3% by weight of plastic, preferably less than 2.5% by weight. These flow-packed chips entered the first feed auger through the first screen inlet at a rate of 200+/-100 kg/h. The first feed auger delivers the wrapping sheet to a cylindrical screen chamber where it is picked up by a rotating blade member and thrown centrifugally against a first screen having an aperture size of 8 mm. The blades on the blade members are mounted in a helical configuration to carry material along the entire length of the first screen. Product passing through the screen below the screen size is collected at the primary screen outlet. This is an intermediate material. To ensure separation of the powder from the plastic, the intermediate material from the first screen is fed into a second screen similar to the first but of 2.4-3.5mm nylon screen, where a second feed auger delivers the product to a second cylindrical screen chamber where it is picked up by a rotating blade assembly and centrifugally projected towards a second screen. The blades on the blade members carry material along the entire length of the screen. Product passing through the screen below the screen size is collected at the primary screen outlet. This is the powder produced. The remaining flow-packed and oversized powder is transported to the end of the classifying chamber and discharged through a separate small outlet.

The equipment specification is as follows: the two screen castings were made of epoxy coated carbon steel. The motor, the coupling and the bearing are located outside the machining area and therefore do not come into contact with the product. A drive shaft made of stainless steel carries a feed auger and blade assembly. For the first screen, the screen frame was designed with 3 ring-shaped 3-steel struts, all welded or bolted in carbon steel or stainless steel, while the second screen was a screen made entirely of nylon.

The product specification is as follows: we used a centrifugal screen for the flow-packed rectangular sheets. The dimensions of the sheet were:

heavy: 53+/-2g, diameter: 54mm, height: 21.5+/-0.25mm, strength of the sheet: 35+/-4 Kpa.The chemical composition a of the uncoated tablets was as follows:

	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
		Tetrasodium salt of hydroxyethane diphosphonic acid	0.73
Soil release agent polymers	0.33
		Fluorescent agent	0.18
Encapsulated zinc phthalocyanine sulphonates	0.025
		Soap powder	1.40
Suds suppressor	1.87
		Citric acid	7.10
EggWhite enzyme	0.79
		Lipase enzyme	0.28
Cellulase enzymes	0.22
		Amylase	1.08
Adhesive dispensing system	1.325
		Total of	100.00

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

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

The cationic agglomerate consisted of 20% cationic surfactant, 56% zeolite and 24% sulfate.

The layered silicate consists of 95% SKS6 and 5% silicate.

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

The ethylenediamine N, N-disuccinic acid sodium/sulfate particles consisted of 58% ethylenediamine N, N-disuccinic acid sodium salt, 23% sulfate and 19% water.

The encapsulated zinc phthalocyanine sulfonate is 10% active.

Suds suppressors were prepared from 11.5% silicone oil (available from Dow Corning); 59% zeolite and 29.5% water.

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

Preparation of tablets:

i) a detergent base powder of composition A was prepared as follows (see table above); all spraying was carried out on the particulate material in the base composition a in a spray drum and then mixed together in a mixing drum to form a uniform particulate mixture.

Ii) then preparing the tablet according to the following method: 53g of the mixture are introduced into a suitably round or rectangular mould and pressed.

Iii) the sheet was immersed in a bath containing 80 parts sebacic acid mixed with 20 parts Nymcel zsb 16. The time for which the sheet was immersed in the heating bath was adjusted to allow 3g of the mixture to be coated thereon. The sheet was then cooled to room temperature at 25 ℃ for 24 hours.

The particle structures of the powders and intermediate materials produced were compared with the particle structure of the original matrix a as follows:

mesh size (μm)	Raw mixture (in each case) Weight deposited on the sieve Volume%)	Intermediate (II)Material (in) Deposited on sieves Weight%)	The obtained powder is prepared by Deposited on sieves Weight%)
				1180	9.66	24.5	8.9
850	24.59	32.7	20.9
				450	64.65	76.9	70.3
250	91.29	91.3	88.1
				150	96.64	96	95
Through 150	3.36	4	5
				Average particle size	500μm	638μm	541μm

The above table should be understood as follows:

9.66% by weight of the raw mixture obtained after step i) above was retained on a 1180 micron sieve, compared to a powder containing 8.9% by weight of material retained on a 1180 micron sieve. 6 sieves (1180, 850, 450, 250 and 150 microns) were placed one on top of the other, with the larger mesh size at the top and the smaller mesh size at the bottom, so that the structure of the particles could be analyzed. The weight percent of particles passing through all screens, i.e., "pass 150", represents the weight percent of fine particles. The table also indicates the average particle size of the material studied.

It should be noted that for the powder produced, the content of fine particles passing through the 150 micron sieve is less than 6% by weight, which is less than 2 times the weight percentage of the particles contained in the raw powder or raw mixture and passing through the 150 micron sieve. It is noted that the tablets described in this example and subjected to the process of the invention were coated and the powder produced was compared with the original powder or blend used to produce the uncoated tablets. The method is also applicable to non-coated sheets.

It should also be noted that the above 6 sieves are used to determine the amount of fine particles contained in the resulting recycled powder, which is generally different from the equipment used in the second or fourth step sieving.

At the end of the second sifter, it was found that there was less than 0.01% by weight of plastic film residues in the powder produced.

Claims (10)

1. A method for preparing a powder from a packaging sheet, said packaging comprising a plastic, whereby the method is characterized in that it comprises a first step: subjecting the packaging sheet to mechanical degradation using a first mechanical degradation device; the second step is as follows: screening by using first screening equipment to obtain an intermediate; the third step: subjecting the intermediate to mechanical degradation with a second mechanical degradation device, and a fourth step: sieving with a second sieving device to obtain a powder, whereby the powder obtained contains less than 0.05% by weight of plastic.

2. A method according to claim 1, wherein the tablet is made by compressing a raw powder.

3. The method according to claim 2, wherein the powder produced comprises a weight percentage of particles passing through the 150 micron sieve which is less than 2 times the weight percentage of particles contained in the raw powder and passing through the 150 micron sieve.

4. A process according to claim 1, wherein the powder produced is added to the raw powder to produce a mixture, the added powder constituting at least 1% and up to 20% by weight of the mixture, the mixture being compressed into tablets.

5. The process according to claim 1, wherein the powder produced comprises less than 4% by weight of particles passing through a 150 micron sieve.

6. The method according to claim 1, wherein the sheet has a tensile strength of less than 100 kilopascals.

7. The method according to claim 1, wherein the mechanical degradation is provided by centrifugation.

8. A method according to claim 1, wherein the packaging sheet comprises at least 1.5% by weight of plastic.

9. The method according to claim 1, wherein the tablet comprises a surfactant.

10. The method according to claim 1, wherein the package is a flow wrap film made of a thermoplastic resin.