LAVATORY CLEANSING COMPOSITION

Abstract: A process for the manufacture of a lavatory cistern block, comprising the steps of extruding a plastified mass through an aperture to form a billet and characterised in that the billet is cut with a chain cutter.

Description: LAVATORY CLEANSING COMPOSITION Technical Field : The present invention relates to toilet blocks and a method of manufacturing the same. Background of the invention: For many years it has been known to provide blocks of a slowly soluble material either in containers attached to the rim of a toilet (so called x rim-blocks ' ) or in the cistern of the toilet (so-called 'cistern-blocks'). The slowly soluble material can comprise a mixture of surfactant and optional filler as well as various functional ingredients such as perfumes dyestuffs and bleaches. Both types of block dissolve slowly in use: the rim block dissolving in the flush water that meets with it when the toilet is flushed and the cistern block dissolving in the water contained in the cistern between flushes. As will be appreciated, the cistern block and the rim block must have distinct solubility characteristics as one spends far more time in contact with water than the other. The solubility characteristics of the blocks can be modified by the inclusion in the blocks of components that modify the rate of solution. Typically, components are added to cistern blocks that significantly reduce the rate of solution to prevent the block completely dissolving in the cistern water for a reasonable period of time. One effect of the addition - 2 - of these components in cistern blocks is to physically harden the block. It has become established practice to manufacture toilet blocks by an extrusion process in which the components of the block are formed by energetic working into a plasticised mass at above ambient temperature that is extruded through a die to form a log or billet. This log or billet is then cut transversely into the individual blocks that harden on cooling. Blocks are generally of a near circular cross section and are cut from the log or billet with a so called 'rotary cutter' shortly after extrusion. The rotary cutter comprises a pivoted member that rotates in the manner of a wind-mill blade and cuts the log or billet into blocks of the desired size. WO 97/47721 (Unilever) discloses toilet blocks that are manufactured by an extrusion process. In order to avoid confusion between rim blocks and cistern blocks it has become commonplace for rim blocks to be long relative to their diameter and cistern blocks to be shaped rather more like an ice-hocked puck or pill-box, i.e. to be somewhat broader than their length along the axis of the log or billet. A manufacturing difficulty arises when cistern blocks contain temperature sensitive components such as bleaching agents, enzymes and particularly volatile perfumes. To prevent decomposition or loss of these components it is desirable to reduce the level of energetic working and/or the extrusion temperature of these blocks . Consequently such blocks generally comprise at least one extrusion aid, - 3 - which can be an oil or an oily material such as a nonionic surfactant. The presence of this material alters the rheological properties of the block and thus it is difficult to cut the blocks with the rotary type of cutter. A similar problem arises when polymers are incorporated into the blocks to modify, that is to reduce the rate of dissolution. In both instances the rotary cutter does not cut the blocks cleanly when the process is operated at reasonable manufacturing speeds and as a result a significant of the blocks formed by this process are malformed and have to be discarded or reworked. Description of the Invention We have determined that the above mentioned difficulties can be overcome by modifying the shape of the cistern blocks so that they comprise square tablets in which the cut surface is preferably not the largest surface of the finished block. These modified tablets are manufactured by extruding a log or billet with a rectangular cross-section and cutting the log or billet with a chain cutter. Accordingly, the present invention provides a process for the manufacture of a lavatory cistern block, comprising the steps of extruding a plastified mass through an aperture to form a billet and characterised in that the billet is cut with a chain cutter. By manufacturing blocks as described above, it is possible to retain the advantages of different shapes for rim and cistern blocks, while obtaining cistern blocks which suffer far less malformation in the manufacturing process. Preferably the cistern-block has a plurality of faces, at least one of said faces being formed by an extrusion process and at least one of said faces being formed by a cutting process, in which the ratio of the maximum to minimum orthogonal dimensions of the block is less than 2.5:1 and that at least one of the faces is formed by a cutting process . It is preferable if the cut face is not the largest face of the block. Detailed Description of the Invention: Typical blocks according to the present invention preferably comprise : a) a bleaching agent or precursor therefor, b) an oily liquid perfume, and, c) a polymer derived from one or more ethylenically unsaturated carboxyl group-containing monomers. It is believed that the combined use of these materials enables the production of a bleaching in-cistern block which has an acceptable in-use lifetime due to improved stability. Without wishing to restrict the invention by reference to any theory of operation it is believed that the polymer forms a protective layer at the surface of the block which retards the access of water to the block and prevents rapid decomposition of the block. However, this polymer is one of the materials which makes these blocks difficult to cut - 5 - using a conventional rotary cutter when the blocks have a conventional pill-box shape. The polymers used in preferred embodiments of the invention are polycarboxylic acids derived from one or more ethylenically unsaturated carboxyl group-containing monomers, especially ethylenically unsaturated carboxylic acids such as acrylic acid or maleic acid. The carboxyl group-containing monomers may be polymerized alone or in combination with other ethylenically unsaturated monomers . The preferred polymers in embodiments of the present invention are those which are readily available in the marketplace. These are polymers of acrylic or methacrylic acid or maleic anhydride, or a co-polymer of one or more of the same either together or with other monomers. In general, polymers derived largely or wholly from the acidic monomers are preferred. Suitable polymers include polyacrylic acid, polymaleic anhydride and copolymers of either of the aforementioned with ethylene, styrene and methyl vinyl ether. Typical polymers are polyacrylic acid and acrylic acid/maleic acid copolymers. In practice the polymers are employed in the form of acids, but can also be employed as salts e.g. alkali metal salts such as the sodium salt. The use of the polymer salts is advantageous if it is required to reduce dust production during formulation and manufacture. It is preferred that the polymer is crosslinked. The cross- linked polyacrylate polymers of the present invention are generally characterised as resins in the form of acrylic acid polymers. Such materials are available from a number of sources including materials available under the tradename CARBOPOL (TM) from B. F. Goodrich Company, the tradename SOKOLAN (TM) from the BASF Corporation and under the tradename POLYGEL (TM) from 3V Sigma. The cross-linked polyacrylate polymers are generally characterised as acrylic acid polymers which are cross-linked with an additional monomer or monomers in order to exhibit an effective molecular weight of one to seven million g/mole. The average formula weight for a polymer sub-unit is preferably of the order of 60-120 g/mole. The polymer is suitably present in an amount of from 0.5 to 20% by weight, more preferably from 1 to 5% by weight, most preferably around 2-3% by weight thereof. Polygel DB (TM) ex 3V Sigma, a cross-linked high molecular weight polyacrylate, has been found to be a suitable material at an inclusion level of around 2-3%wt. Surfactants : Preferably, the blocks will also contain a surfactant component which may be anionic or nonionic in nature. The surfactant serves to provide a cleansing and foaming effect and may, also act synergistically with the polymer component. Typically, surfactant comprises up to 50%wt of the composition. Preferably, the surfactant component comprises one or more anionic surface active agents, optionally in combination with one or more nonionic surface active agents. Suitable - 7 - anionic surface active agents include alkali metal or ammonium alkylaryl sulphonates (especially alkyl benzene sulphonates) , alkane sulphonates, alkyl sulphates and sarcosinates . We have determined that improved foaming properties are obtained by the use of a surfactant system which comprises primary alkyl sulphate (PAS) together with other anionic surfactants. Preferably the present invention provides a lavatory cistern block comprising l-15%wt (more preferably l-5%wt) of a primary alkyl sulphate and 15-50%wt (more preferably 30-50%wt) of other anionic surfactants. We have determined that the use of this mixed surfactant system is advantageous in that it reduces the stickiness of the block during manufacture. The blocks with 1-5% PAS show improved wear characteristics. Preferably said other anionic surfactants is a sulphonate. Suitable sulphonates include alkyl benzene sulphonate (ABS) . It is believed that the combination of relatively low levels of PAS together with higher levels of ABS promotes the foaming and the perfume delivery from the block. PAS is also believed to be environmentally more acceptable than alkyl benzene sulphonate . Suitable nonionic surfactants include polyethoxylated fatty alcohols, polyethoxylated fatty acids, polyethoxylated alkyl phenols, amine oxides and ethylene oxide/propylene oxide block copolymers . The total amount of surfactant when present, may lie within wide limits. In practice, the surfactant will generally for 10 to 70% by weight of the composition, but more preferable that surfactant comprises from 20 to 50% by weight thereof. Process Aids : Optionally, the blocks according to the invention further comprise a processing aid to assist in extrusion. Suitable processing aids include oils (including both mineral and silicone oils) , esters (other than those derived from ethylenically unsaturated carboxyl group-containing monomers) and polybutene. One particularly suitable processing aid is an alkoxylated alcohol. It is preferred that the alkoxylated alcohol is an ethoxylated alcohol . The preferred level of alkoxylated alcohol is 0.75-2%wt. The preferred ethoxy chain length is 40-60 with an average ethoxy chain length of around 50 being preferred. Suitable materials include Empilan KM 50 /KF (TM) ex. Albright & Wilson. Another suitable process aid is a PEG monostearate. PEG 4000 Monostearate (100%) ex DAC is a suitable raw material. Fillers: Typically, blocks according to the present invention comprise 0 to 50% by weight of an inert non-polymeric and/or electrolyte filler. Preferably blocks contain 5-50%wt, more preferably 10-30% of filler. Suitable fillers include one or more of urea, sodium, magnesium and calcium carbonates, sodium chloride, borax, - 9 - talc and sodium, magnesium and calcium sulphates . Preferred ionic fillers include sodium sulphate. Preferred inert, non- polymeric fillers include calcium carbonate. Typical levels of total filler range from 10-40%wt on product in total. It has been found useful, for ease of formulation and to ensure complete solubility of in-cistern blocks, to employ 10-30%wt of an ionic filler as the sole filler present. For mixed filler systems, preferred levels of filler are 10- 20%wt on product of ionic filler and 10-20% on product of inert filler. It is particularly preferred to use an approximately 50:50 mixture of sodium sulphate and calcium carbonate as the filler. For mixed filler systems typical levels in product are 15%wt of each of calcium carbonate and sodium sulphate. Bleaching Agents : Typically the blocks comprise up to 50% by weight of an at least sparingly water soluble bleaching agent. Typical levels of bleaching agents are 2-30%wt on product. For the purposes of the present specification the term bleaching agent is used to mean both a bleaching agent and a precursor which produces a bleaching agent unless the context demands otherwise . Suitable bleaching agents active-halide and active-oxygen bleaching agents, particularly the so-called 'halogen release agents ' . - 10 - Chlorine bleaching agents are preferred. Suitable water- soluble, active chlorine, bleaching agents used in accordance with the invention include chlorinated cyanurates, phthalimides, p-toluene sulphonamides , azodicarbonamides, hydantoins, glycoluracils, amines and melamines . The alkali metal salts of cyanurates are preferred. A particularly preferred bleaching agent is sodium dichlorocyanurate (NaDCCA) . The bleaching agent is typically present in an amount of 10-30% and most preferably at around 25%. Oxidan DCN/WSG (TM) ex Sigma has been found to be a suitable bleaching agent. Perfume : Preferably, the blocks comprise 2-15%wt of a hydrophobic oily liquid perfume. The blocks more preferably comprise, 2- 10%, more preferably 3-6%wt of the perfume. Levels of around 4%wt perfume are particularly preferred. This oily perfume is typically of the kind described in the European patent application EP 167,210. It will be understood that the liquid oily perfume must be stable in the presence of the water-soluble, active chlorine, bleaching agent. Suitable oily perfumes can be easily selected by testing them in combination with the water-soluble, active chlorine, bleaching agent. Examples of suitable bleach-stable perfumes are Verdeo 898, Bonanza 048 and Ponderosa 431 all ex IFF, and LB 132 ex Quest. Particularly preferred perfumes are Icebreaker Super - 11 - Mod, Oxygen Supra Mod, Motebianco Supra and lemonfit Supra (all TM) ex Givaudan Roure . The most preferred perfume is Green Tank Harder (TM) ex. Givaudan Roure. Minors : Minor components will generally be present but are optional. These include colouring agents, and/or whiteners. These materials should be chosen such that they are compatible with the bleaching agent and do not react therewith to a significant extent. We have determined that ' Sudangelb 150' (TM) ex. Sandoz is an acceptable colouring agent as are Colanyl Green (TM) ex Hoechst and Dispers Blue (TM) ex BASF. A particularly preferred colouring agent is P. Green (CI 74260 ) . Titanium dioxide is an acceptable whitener. Levels of colouring agents and/or whiteners as typically below 5%wt. For colouring agents levels are typically in the range 0.0001-0. l%wt. Further enhancement of the product may be obtained by the additional use of chelating agent, sequestrant or water- softening agent such as ethylene diamine tetra-acetic acid or a derivative thereof, nitrolotriacetic acid, phosphonates of polyphosphates, metasilicates, boroheptonates, s.s- thylene-diamino disuccinate, dipicolinic acid, 2- phosphonobutane-1, 2 , 4-tricarboxylic acid, or lower molecular weight polymeric materials capable of inhibiting crystal growth. Further reducing agents, such as alkali metal metabisulphates may be present to assist in the reduction of staining due to metals such as iron. - 12 - An optional minor component is a foam-boosting surfactant, Suitable surfactants include amine oxides. Process : As noted above, compositions in accordance with the invention are formed by an extrusion process in which the mixture of the components is extruded as a plastified mass through an aperture to form a billet and said billet is cut into tablets of appropriate size by means of a chain cutter. It is preferred if the aperture through which the plastified mass is extruded has an orthogonal shape, it is especially preferred if the aperture is a square. The chain cutter used in the invention is described further hereinafter, by way of example only, with reference to the accompanying drawing in which figure 1 shows a cross section of the chain cutter. In particular the illustrated embodiment of the chain cutter comprises evenly placed blades (1) on a linked chain (2). During operation the linked chain and blades are rotated by means of two cylindrical rotors (3) and thus the blades cut the extruded billet (4) into tablets (5). When extruding a solid composition it is generally advantageous, as noted above, that some lubricant component or process aid be present to facilitate extrusion. It is preferred if the cutting step is followed by a cooling step such that the cooling step takes place on a cooling - 13 - belt and the lavatory cistern block remains on the cooling belt for at least 5 minutes. The degree of hardness of the block may play an important part on the ease of cutting it. To this effect it is advantageous if the finished block has a degree of hardness of 11 to 17 Kg, preferably 12 to 16 Kg as measure by a penetrometer . This method of measuring hardness entails placing a toilet block on a balance and lowering a penetration sphere (diameter 1 cm) onto the block. The balance then measures the force at which the penetration sphere penetrates the block. The higher the reading the harder the block. It is preferred that if the compositions of the invention are used as free-standing lavatory cleansing blocks, they have a weight from 30 to 150gms, preferably 40-80gm. Preferred Compositions Preferred embodiments of the invention provide a slow- release lavatory cleansing block comprising: a) 2-30%wt of a halogen release agent, b) 2-15% wt of an oily liquid perfume, and, c) l-5%wt of a polymer derived from one or more ethylenically unsaturated carboxyl group-containing monomers . Particularly preferred compositions are: a) l-5%wt primary alkyl sulphate b) 30-50%wt alkyl benzene sulphonate - 14 - c) 10-30%wt NaDCCA d) 10-30%wt sodium sulphate, calcium carbonate or a mixture thereof, e) 2-10%wt oily liquid perfume f) l-5%wt water insoluble, gelling, cross linked polyacrylate , g) 0-5%wt colour and/or optical brightener. The invention also provides a method of cleaning a lavatory or urinal using a block of a composition in accordance with the invention. In order that the invention may well be understood, the following Examples are given by way of illustration only. Examples : Blocks having the compositions listed in Table 1 below were made up by an extrusion process, followed by cutting with a chain cutter and cooling on a cooling belt. All amounts are expressed as percentages by weights . The materials employed were: Alkyl benzene sulphonate NANSA HS 80/LPF [TM] ex. Albright & Wilson 15 Primary alkyl sulphate EMPICOL LZ-V [TM] ex. Albright Wilson Polymer Polygel DB [TM] high molecular weight, water-insoluble, partially cross-linked acrylic acid polymer ex. Sigma. NaDCCA OXIDAN DCN/WSG [TM] ex Sigma Perfume Green Tank Harder [TM] ex Givaudan Roure. TABLE 1 Example: 1 wt Alkyl benzene sulphonate 37 Primary alkyl sulphate 4.5 Polygel DB 3.0 NaDCCA 25 Sodium sulphate 13.25 Perfume 4.0 Minors to 100% The block gave satisfactory performance.

Claims: - 16 - CLAIMS : 1. A process for the manufacture of a lavatory cistern block, comprising the steps of extruding a plastified mass through an aperture to form a billet and characterised in that the billet is cut with a chain cutter. 2. A process for the manufacture of lavatory block according to claim 1 in which the plastified mass is extruded through an orthogonal aperture . 3. A process for the manufacture of lavatory cistern block according to claim 1 or claim 2 in which the block is cut followed by cooling on a cooling belt. 4. A cistern-block manufactured according to any preceding claim, the block having a plurality of faces, at least one of said faces being formed by an extrusion process and, in which the ratio of the maximum to minimum orthogonal dimensions of the block is less than 2.5:1 and in which at least one of said faces is formed by a cutting process. 5. A cistern-block according to claim 4 in which the cut face is not the largest face of the block. 6. A cistern block according to claim 4 or claim 5 which comprises a bleaching agent. - 17 - 7. A cistern block according to claim 6 in which the bleaching agent is selected from chlorinated cyanurates, phthalimides, p-toluene sulphonamides, azodicarbonamides, hydantoins, glycoluracils, amines and melamines . 8. A cistern block according to claim 7 in which the bleaching agent is sodium dichlorocyanurate (NaDCCA) . 9. A cistern block according to any one of claims 4 to 8, further comprising a processing aid selected from mineral oil, silicone oil, water insoluble esters other than those derived from ethylenically unsaturated carboxyl group- containing monomers , polybutene and alkoxylated alcohols. 10. A cistern block according to any one of claims 4 to 9 comprising: a) 1-5% wt primary alkyl sulphate b) 30-50% wt alkyl benzene sulphonate c) 10-30% wt NaDCCA d) 10-30% wt sodium sulphate, calcium carbonate or a mixture thereof, e) 2-10% wt oily liquid perfume

Inventors: BOLZONI GIUSEPPE VINCENZO, DEAN DAVID JAMES, MCGOVERN JAMES THOMAS, MORRIS RONALD MEREDITH, REBAGLIATI MAURIZIO, TUMMIOLO ROBERTO, BOLZONI, GIUSEPPE, VINCENZO, DEAN, DAVID, JAMES, MCGOVERN, JAMES, THOMAS, MORRIS, RONALD, MEREDITH, REBAGLIATI, MAURIZIO, TUMMIOLO, ROBERTO
Applicants: BOLZONI GIUSEPPE VINCENZO, DEAN DAVID JAMES, LEVER HINDUSTAN LTD, MCGOVERN JAMES THOMAS, MORRIS RONALD MEREDITH, REBAGLIATI MAURIZIO, TUMMIOLO ROBERTO, UNILEVER NV, UNILEVER PLC, BOLZONI, GIUSEPPE, VINCENZO, DEAN, DAVID, JAMES, HINDUSTAN LEVER LIMITED, MCGOVERN, JAMES, THOMAS, MORRIS, RONALD, MEREDITH, REBAGLIATI, MAURIZIO, TUMMIOLO, ROBERTO, UNILEVER N.V.
Application year: 1999
Main classification: C11D3
IPC codes: C11D1, C11D3, C11D17