AU646018B2

AU646018B2 - Liquid bleach composition

Info

Publication number: AU646018B2
Application number: AU72109/91A
Authority: AU
Inventors: Theresia Maria Olsthoorn; Johannes Cornelis Van De Pas
Original assignee: Unilever PLC
Current assignee: Unilever PLC
Priority date: 1990-02-08
Filing date: 1991-02-07
Publication date: 1994-02-03
Anticipated expiration: 2011-02-07
Also published as: WO1991012307A3; CA2073445A1; EP0514422A1; ES2072601T3; JPH0768542B2; DE69109273D1; EP0514422B1; DE69109273T2; BR9105999A; WO1991012307A2; AU7210991A; JPH05502908A

Description

LIQUID BLEACH COMPOSITION The present invention relates to a liquid detergent composition comprising an aqueous base, detergent active materials and a bleach material.

It has been proposed in EP 293 040 to formulate liquid detergent compositions comprising a perbcrate bleach material and a water-soluble solvent system to increase the stability of the bleach in the aqueous phase. Similar solvents in combination with bleaches are proposed in EP 294 904 In formulating liquid aqueous detergent compositions comprising a bleach material, we have noted that bleach instability problems sometimes occur. Although not yet fully understood this instability is believed to be caused by the solubilisation of the bleach materials in the aqueous phase, followed by the decomposition of the dissolved bleach materials.

Surprisingly it has now been found that stable bleach containing liquid aqueous detergent compositions can be formulated, provided that said compositions also comprise a specific silicate stabilising material.

Sh Accordingly, the present invention relates 4 a liquid detergent composition comprising an aqueous base containing from 10-30% by weight of detergent active material., from 1-40% by weight r Fdec rol Ae. rP CohSISsit9 or oerborafe cd /er-ccirboke bchaces of a -e paiL eroxygen bleach 'aterialAand from 0.4 to 5 by weight of alkali metal silicate material, preferably a disilicate material.

SUBSTITUTE

SHEET

bleach material Compositions according to the present invention comprise a c. /c -frv perbor.et awd perbr tebleach material, which is a peroxygen bleach 4 This bleach component may be present in the system in dissolved form, but preferred is that only part of the peroxygen bleach is solubilized, the remaining part preferably being present as solid peroxygen particles which are suspended in the system.

Examples of suitable ble.ach compounds include the pcrboratez, persulfates, peroxy disulfates, perphosphates and t crystalline peroxyhydrates formed by re c'hydrogen peroxide with urea or alkali .e carbonate. Also encapsulated blea may be used. Preferred bleaches are only parti soluble in the system. Especially preferred is the use of perborate or percarbonate bleachoo.

The bleach component is preferably added in an amount corresponding to 0.1 to 15% by weight of active oxygen, more preferred from 0.5 to 10% active oxygen, typically from 1.0 to active oxygen. Typical amounts of bleach will be between 1 and 40 by weight of the aqueous composition, more preferred from 7 to 30%, especially preferred from 10 to 25 by weight of the composition.

silicate material Compositions of the invention also comprise an alkali metal silicate material. Suitable silicate materials are for example sodium and potassium silicates, for example sodium metasilicate and sodium disilicates. The use of alkali metal disilicates is preferred.

SUBSTITUTE SHEET o Although not yet fully understood it is believed that the alkali metal silicate material can have two functions, firstly it prevents the solubilisation of the bleach material, therewith minimizing the amount of instable dissolved bleach and secondly it retards the decomposition of the dissolved bleach materials.

The level of alkali metal silicate material is prof blyfrom 0.4 to 5 detergent active materials Compositions of the present invention also comprise detergent active materials. Surprisingly it has been found that a combination of bleach materials and alkali metal silicate materials is suitable for use in ready to use aqueous liquid detergent compositions.

In the widest definition the detergent active materials in general, may comprise one or more surfactants, and may be selected from anionic, cationic, nonionic, zwitterionic and amphoteric species, and (provided mutually compatible) mixtures thereof. For example, they may be chosen from any of the classes, sub-classes and specific materials described in "Surface Active Agents" Vol. I, by Schwartz Perry, Interscience 1949 and "Surface Active Agents" Vol. II by Schwartz, Perry Berch (Interscience 1958), in the current edition of "McCutcheon's Emulsifiers Detergents" published by the McCutcheon division of Manufacturing Confectioners Company or in Tensid-Taschenburch", H. Stache, 2nd Edn., SUBSTITUTE SHEET W091/12307 PCTiP9 1/00258 4 Carl Hanser Verlag, Munchen Wien, 1981.

Suitable nonionic surfactants include, in particular, the reaction products of compounds having a hydrophobic group and a reactive hydrogen atom, for example aliphatic alcohols, acids, amides or alkyl phenols with alkylene oxides, especially ethylene oxide either alone or with propylene oxide. Specific nonionic detergent compounds are alkyl (C 6

-C

18 primary or secondary linear or branched alcohols with ethylene oxide, and products made by condensation of ethylene oxide with the reaction products of propylene oxide and ethylenediamine. Other so-called nonionic detergent compounds include long chain tertiary amine oxides, long chain tertiary phosphine oxides and dialkyl sulphoxides.

Also possible is the use of salting out resistant active materials, such as for example described in EP 328 177, especially the use of alkyl poly glycoside surfactants, such as for example disclosed in EP 70 074.

Suitable anionic surfactants are usually water-soluble alkali metal salts of organic sulphates and sulphonates having alkyl radicals containing from about 8 to about 22 carbon atoms, the term alkyl being used to include the alkyl portion of higher acyl radicals. Examples of suitable synthetic anionic detergent compounds are sodium and potassium alkyl sulphates, especially those obtained by sulphating higher (C 8

-C

18 alcohols produced for example from tallow or coconut oil, sodium and potassium alkyl (C 9

-C

20 benzene sulphonates, particularly sodium linear secondary alkyl (C 10

-C

15 benzene sulphonates; sodium alkyl glyceryl ether sulphates, especially those ethers of the higher alcohols derived from tallow or coconut oil and synthetic alcohols derived from petroleum; sodium coconut oil fatty monoglyceride sulphates and acid esters of higher (C 8

-C

18 fatty alcohol-alkylene oxide, particularly ethylene oxide, reaction products; the reaction products of fatty acids such as coconut fatty acids esterified with isethionic acid and neutralised with sodium hydroxide; sodium and potassium salts of fatty acid amides of methyl taurine; alkane monosulphonates such as those derived by reacting alpha-olefins (C 8

-C

20 with sodium bisulphite and those derived from reacting paraffins with SO 2 and C12 and then hydrolysing with a base to produce a random sulphonate; and olefin sulphonates, which term if used to describe the material made by reacting olefins, particularly C 10

-C

20 alphaolefins, with S03 and then neutralising and hydrolysing the reaction product. The preferred anionic detergent compounds are sodium (Ci 1

-C

15 alkyl benzene sulphonates and sodium or potassium primary (CIo-C 18 alkyl sulphates.

It is also possible, and sometimes preferred, to include an alkali metal soap of a fatty acid, especially a soap of an acid having from 12 to 18 carbon atoms, for example oleic acid, ricinoleic acid, and fatty acids derived from castor oil, alkylsuccinic acid, rapeseed oil, groundnut.oil, coconut oil, palmkernel oil or mixtures thereof. The sodium or potassium soaps of these acids can be used.

The total detergent active material will be present at from to 30% by weight of the total composition.

SUBSTITUTE

SHEET

WO 91/12307 PCT/EP91/00258 6 optional ingredients Compositions of the invention may be un-structured (isotropic) or structured. Structured liquids of the invention may be internally structured whereby tae structure is formed by the detergent active materials in the composition or externally structured, whereby the structure is provided by an external structurant.

Preferably compositions of the invention are internally structured.

Some of the different kinds of active-structuring which are possible are described in the reference H.A. Barnes, "Detergents", Ch.2. in K. Walters "Rheometry: Industrial Applications", J. Wiley Sons, Letchworth 1980. In general, the degree of ordering of such systems increases with increasing surfactant and/or electrolyte concentrations. At very low concentrations, the surfactant can exist as a molecular solution, or as a solution of spherical micelles, both of these being isotropic. With the addition of further surfactant and/or electrolyte, structured (antisotropic) systems can form. They are referred to respectively, by various terms such as rod-micelles, planar lamellar structures, lamellar droplets and liquid crystalline phases. Often, different workers have used different terminology to refer to the structures which are really the same. For instance, in European patent specification EP-A-151 884, lamellar droplets are called "spherulites". The presence and identity of a surfactant structuring system in a liquid may be determined by means known to those skilled in the art for-example, optical techniques, various rheometrical measurements, x-ray or neutron diffraction, and sometimes, electron microscopy.

When the compositions are of lamellar droplet structure WO 91/12307 PCT/EP91/00258 7 then in many cases it is preferred for the aqueous continuous phase to contain dissolved electrolyte. As used herein, the term electrolyte means any ionic water soluble material. However, in lamellar dispersions, not all the electrolyte is necessarily dissolved but may be suspended as particles of solid because the total electrolyte concentration of the liquid is higher than the solubility limit of the electrolyte. Mixtures of electrolytes also may be used, with one or more of the electrolytes being in the dissolved aqueous phase and one or more being substantially only in the suspended solid phase. Two or more electrolytes may also be distributed approximately proportionally, between these two phases. In part, this may depend on processing, e.g.

the order of addition of components. On the other hand, the term "salts" includes all organic and inorganic materials which may be included, other than surfactants and water, whether or not they are ionic, and this term encompasses the sub-set of the electrolytes (water soluble materials).

The selection of surfactant types and their proportions, in order to obtain a stable liquid with the required structure will be fully within the capability of those skilled in the art. However, it can be mentioned that an important sub-class of useful compositions is those where the detergent active material comprises blends of different surfactant types. Typical blends useful for fabric washing compositions include those where the primary surfactant(s) comprise nonionic and/or a nonalkoxylated anionic and/or an alkoxylated anionic surfactant.

In the case of blends of surfactants, the precise proportions of each component which will result in such stability and viscosity will depend on the type(s) and anount(s) of the electrolytes, as is the case with WO 91/12307 PCT/EP91/00258 8 conventional structured liquids.

Preferably though, the compositions contair from 1% to especially from 10 to 45% of a salting-out electrolyte. Salting-out electrolyte has the meaning ascribed to in specification EP-A-79 646, that is salting-out electrolytes have a lyotropic number of less than 9.5. Optionally, some salting-in electrolyte (as defined in the latter specification) may also be included, provided it is of a kind and in an amount compatible with the other components and the composition is still in accordance with the definition of the invention claimed herein. Some or all of the electrolyte (whether salting-in or salting-out), or any substantially water insoluble salt which may be present, may have detergency builder properties. In any event, it is preferred that compositions according to the present invention include detergency builder material, some or all of which may be electrolyte. The builder material is any capable of reducing the level of free calcium ions in the wash liquor and will preferably provide the composition with other beneficial properties such as the generation of an alkaline pH, the suspension of soil removed from the fabric and the dispersion of the fabric softening clay material. Preferably the salting-out electrolyte comprises citrate.

Examples of phosphorous-containing inorganic detergency builders, when present, include the water-soluble salts, especially alkali metal pyrophosphates, orthophosphates, polyphosphates and phosphonates. Specific examples of inorganic phosphate builders include sodium and potassium tripolyphosphates, phosphates and hexametaphosphates. Phosphonate sequestrant builders may also be used.

Examples of non-phosphorus-containing inorganic WO 91/12307 PCT/EP91/0025 8 9 detergency builders, when present, include watersoluble alkali metal carbonates, bicarbonates, silicates and crystalline and amorphous aluminosilicates. Specific examples include aodium carbonate (with or without calcite seeds), potassium carbonate, sodium and potassium bicarbonates and zeolites.

In the context of inorganic builders, we prefer to include electrolytes which promote the solubility of other electrolytes, for example use of potassium salts to promote the solubility of sodium salts. Thereby, the amount of dissolved electrolyte can be increased considerably (crystal dissolution) as described in UK patent specification GB 1 302 543.

Examples of organic detergency builders, when present, include the alkaline metal, ammonium and substituted ammonium polyacetates, carboxylates, polycarboxylates, polyacetyl carboxylates and polyhydroxysulphonates.

Specific examples include sodium, potassium, lithium, ammonium and substituted ammonium salts of ethylenediaminetetraacetic acid, nitrilitriacetic acid, oxydisuccinic acid, CMOS, TMS, TDS, melitic acid, benzene polycarboxylic acids and citric acid.

Preferably the level of non-soap builder material is from 0-50% by weight of the composition, more preferred from 5-40%, most preferred 10-35%.

In the context of organic builders, it is also desirable to incorporate polymers which are only partly dissolved, in the aqueous continuous phase as described in EP 301.882. This allows a viscosity reduction (due to the polymer which is dissolved) whilst incorporating a sufficiently high amount to achieve a secondary benefit, especially building, because the part which is not dissolved does not bring about the instability that WO 91/12307 WO 91/12307 PCT/EP91/00258 would occur if substantially all were dissolved. Typical amounts are from 0.5 to 4.5% by weight.

It is further possible to include in the compositions of the present invention, alternatively, or in addition to the partly dissolved polymer, yet another polymer which is substantially totally soluble in the aqueous phase and has an electrolyte resistance of more than 5 grams sodium nitrilotriacetate in 100ml of a 5% by weight aqueous solution of the polymer, said second polymer also having a vapour pressure in 20% aqueous solution, equal to or less than the vapour pressure of a reference 2% by weight or greater aqueous solution of polyethylene glycol having an average molecular weight of 6000; said second polymer having a molecular weight of at least 1000. Use of such polymers is generally described in our EP 301,883. Typical levels are from 0.5 to 4.5% by weight.

The viscosity of compositions according to the present is preferably less than 1,500 mPa.s, more preferred less than 1,000 mPa.s, especially preferred between 30 and 900 mPa.s at 21 s 1 One way of regulating the viscosity ani stability of compositions according to the present invention is to include viscosity regulating polymer.c materials.

Viscosity and/or stability regulating polymers which are preferred for incorporation in compositions according to the invention include deflocculating polymers having a hydrophilic backbone and at least one hydrophobic side chain. Such polymers are for instance described in our copending European application EP 89201530.6 (EP 346 995).

Deflocculation polymers for use in detergent WO91/17307 PCT/EP91/00258 1( formulations according to the present invention may be of anionic, nonionic or cationic nature. Anionic deflocculating polymers are preferred.

The hydrophilic backbone of the polymer is typically a homo-, co- or ter-polymer containing carboxylic acVd groups (or more preferably) salt forms thereof), Ae.g.

maleate or acrylate polymers or co-polymers of these together or with other monomer units such as Vinyl ethers, styrene etc. The hydrophobic chain or chains typically are selected from saturated and unsaturated alkyl chains, e.g. having from 5 to 24 carbon atoms and are optionally bonded to the backbone via an alkoxylene or polyalkoxylene linkage, for example a polyethoxy, polypropoxy or butyloxy (or mixtures of same) linkage having from 1 to 50 alkoxylene goups. Thus, in some forms, the side chain(s) will essentially have the character of a nonionic surfactant. Preferred anionic polymers are disclosed in our copending European patent application EP 89201530.6 (EP 346 995).

Preferably the amount of viscosity regulating polymer is from 0.1 to 5% by weight of the total composition, more preferred from 0.2 to 2%.

Compositions of the invention may also comprise materials for adjusting the pH. For lowering the pH it is preferred to use weak acids, especially the use of organic acids is preferred, more preferred is thl use of C 1-8 carboxylic acids, most preferred is the use of citric acid. The use of these pH lowering agents is especially preferred when the compositions of the invention contain enzymes such as amylases, proteases and lipolases.

Apart from the ingredients already mentioned, a number o-f OCf-ioi( 'ingreOieAfs May also be preen+ tor ezample 12 lather boosters such as alkanolamides, particularly the monoethanolamides derived from palm kernel fatty acids and coconut fatty acids, fabric softeners such as clays, amines and amine oxides, lather depressants, inorganic salts such as sodium sulphate, and, usually present in very minor amounts, fluorescent agents, perfumes, germicides colourants and enzymes such as proteases, cellulases, amylases and lipases (including Lipolase (Trade Mark) ex Novo). Suitable examples of protease enzymes are Savinase® (ex Novo), Maxacal® (Gist- Brocades), Opticlean® (ex MKC) or AP122® (ex Showa Denko), Alcalase®, Maxatase®, Esperase®, Optimase®, proteinase K and subtilisin BPN. Suitable lipases are for example Lipolase® (ex Novo), Amano lipases, Meitc' lipases, Lipozym®, SP 225, SP 285, Toyo Jozo lipase.

Suitable amylases are for example Termamyl® (TM of Novo) and Maxamyl®. Suitable cellulases include Celluzym® (ex Novo).

Compositions of the inventior preferably comprise from -80 by weight of water, more preferably'from most preferably from 20-50 Liquid detergent compositions according to the invention are preferably physically stable in that they show less than 2% by volume phase separation upon storage for 21 days after preparation at 25 0

C.

Liqu'd detergent compositions according to the invention are preferably volume stable in that they show less than preferably less than 10%, more preferably less than volume increase during storage at a temperature between 20 and 37 0 C for a period of three months after preparation.

For obtaining good volume stability, preferably the compositions according to the present invention also comprise a second stabilising agent for the bleach SUBSTITUT E SHEET component. Suitable stabilisers are well-known in art and include EDTA, Magnesium silicates and phosphonates such as for instance the Dequest® range ex Monsanto and Naphthol® ex Merck. Preferably the amount of these stabilising agents is from 0.05 to 5 by weight of the composition, more preferred from 0.05 to 1% of the composition.

Compositions of the present invention may comprise one or more bleach precursor agents. A well-known example of such an agent is TAED. Preferably the bleach precursor agent is present in the system in at least partly undissolved form. One way of ensuring that the precursor is present in undissolved form is to increase the amount of electrolyte in the composition, therewith reducing the solubility of the precursor in the system. Suitable electrolytes for this purpose are for instance the at least partially water soluble carbonate, sulphate and halogenide salts.

In use the detergent compositions of the inventention will be diluted with wash water to form a wash liquor for instance for use in a washing machine. The concentration of liquid detergent composition in the wash liquor is preferably from 0.05 to 10 more preferred from 0.1 to 3% by weight.

To ensure effective detergency, the liquid detergent compositions preferably are alkaline, and it is preferred that they should provide a pH within the range of about 7.0 to 12, preferably about 8 to about 11, when used in aqueous solutions of the composition at the recommended concentration. To meet this requirement, the undiluted liquid composition should preferably be of a pH above 7, for example about pH 8.0 to about 12.5. It should be noted that an excessively high pH, e.g. over about pH 13, is less desirable for domestic safety. If FiUBSTITUr i SHEET WO91/12307 PCT/EP91/00258 14 hydrogen peroxide is present in the liquid composition, then the pH is generally from 7.5 to 10.5, preferably 8 to 10, and especially 8.5 to 10, to ensure the combined effect of good detergency and good physical and chemical stability. The ingredients in any such highly alkaline detergent composition should, of course, be chosen for alkaline stability, especially for pH-sensitive materials such as enzymes, and a particularly suitable proteolytic enzyme. The pH may be adjusted by addition of a suitable alkaline or acid material.

Compositions according to the invention may be prepared by any method for the preparation of liquid detergent compositions. A preferred method involves the addition of the alkali metal silicate to water, which optionally comprises one or more of the other ingredients of the formulation. The bleach materials are preferably added as a pre-dispersion The invention will now be illustrated by way of the following Examples. In all Examples, unless stated to the contrary, all percentages are by weight.

WO 91/12307 PCT/EP91/00258 Example I The following composition was prepared by adding the ingredients in the listed order to water: Ingredient (wt parts) Na disilicate Na perborate .4 H 2 0 water dissolved bleachl) half life time in days at 37°C decomposed bleach 3

A

49.5 1.9 352) 0.027 2.1 <<1 >1.65 1) wt of dissolved perborate in isolated electrolyte phase at t=0, and at room temperature 2) extrapolated.

3) in weight of the total bleach in the isolated electrolyte phase after 1 day.

Composition A had a pH of about 11 and contained about 1.9 by weight of the bleach material in solubilised form, the half-life time of the bleach at 37 0 C was days. Composition B had a pH of about 9.8 and contained about 2.1 by weight of the bleach material in solubilised form. The half-life time of the dissolved bleach was significantly less than 1 day.

This example clearly illustrates that alkali metal disilicates can advantageously be used for the stabilisation of bleach.

Example II The following liquid formulated by adding listed order: Ingredient Na DOBS Synperonic® A7 Na Oleate Glycerol Na-disilicate

STP

Na-perborate. 4H 2 0 Polymer water detergent conpositions may be the ingredients to water in the Basic formulation wt) 1 2 3 8.5 8.5 7.5 2.0 2.0 3.0 2.7 10.8 8.1 5.0 5.0 5.0 3.5 3.5 3.5 22 22 22 15 10 12 1.0 1.0 1.0 up to 4 7.5 4.3 3.0 10.8 5.0 3.5 22 22 10 0.5 100---- Polymer A-2 as described in EP (EP 346 995).

89201530.6 SUBSTITUTE SHEET Example III The following compositions were made by adding the electrolyte together with the minor ingredients except for the perfume and the enzymes to water of elevated temperature, followed by the addition of the deflocculating polymer and then the detergent active materials as a pre-mix under stirring and thereafter coolin. the mixture and adding the enzymes and the perfumes.

INGREDIENT (%wt) NaLas Synperonic® A7 Na-disilicate Na-citrate 2aq Dequest® 2060S(100%) Perborate tetra Alcalase® CaCl 2 2H 2 0 Tinopal® CBS-X Silicon DB 100 Perfume polymer water pH

A

21 9 1 10.3 0.4 20 0.75 0.15 0.1 0.25 0.3

B

21 9 4 10.3 0.4 20 0.75 0.15 0.1 0.25 0.3 C D 21 21 9 9 1 10.3 0.4 20 0.75 0.15 0.1 0.25 0.3 4 10.3 0.4 0.75 0.15 0.1" 0.25 0.3 1 1 1 1 balance 9 9 11 11 The perborate was added as a 65 predispersion in water (Proxsol® ex ICI), the polymer was a deflocculating polymer described as A44 in EP 346 995, the pH was adjusted, if necessary, with citric acid.

The viscosity of the products was measured in mPa.s at 21 s-1; the volume stability was determined by measuring the maximum volume increase during storage of three months at ambient temperature; the physical stability was determined by checking the phase separation and solid SUBSTITUTE

SHEET

WO 91/12307 PCT/EP91/00258 18 sedimentation upon storage; the Bleach stability indicates the percentage of bleach left after storage of 4 weeks at 37 The following results were obtained: Viscosity Volume stab.

Physical stab.

-phase sep.

-solid sed.

Bleach stab.

I

A B C D 1230 4830 1250 4870 0% >14% 0% 0% stable stable 93% 95% 92% These results indicate that good bleach stability can be obtained when using an alkali metal disilicate in combination with bleach.

Claims

1. A liquid detergent composition comprising an aqueous base containing from 10-30% by weight of detergent active materials, from 1-40% by weight of a peroxygen bleach material selected from the group consisting of perborate and percarborate bleaches and from 0.4 to 5% by weight of alkali metal silicate material.

2. A liquid detergent composition according to claim 1, wherein the alkali metal silicate material is an alkali metal desilicate.

3. A liquid detergent composition according to claim 1, comprising from 7-30% by weight of said bleach material. *i I o A liquid detergent composition according to claim 1, comprising 5-40% by weight of a non-soap builder material. *4j SUBSTITUTE SHEET INTERNATION~AL SEARCH REPORT International Application No PCT /EP 9 1 025 8 I. CLASSIFICATION OF SUBJECT MATTER (it several classific3iion symbols apply, *ndicale ami According to International Patent Classification (IiPC) or to both Nationai Classification and IPC :C 11 D 3/39, C 11 D 3/08 If. FIELDS SEARCHED Minimum Documentation Searched Classification System Classification Symbols IPC C 11D Documentation Searched other than Minimum Documentation to the Extent that such Documents are Included In the Fields Searched Ill. DOCUMENTS CONSIDERED TO BE Category Citation of Document, 11 with Indication, where appropriate. ot the retevant passages i2 Relevant to Claim No. i2 X EP, A, 0346994 (UNILEVER-) 1,2,6,9 December 1989 see page 3, line 47; page 4, lines 1-2; claims P,X EP, A, 0368575 (ICI) 1-4 16 May 1990 see the claims P,X EP, A, 0359308 (UNILEVER) 1,2,6 21 March 1990 see page 9, line 36; page 10, line 7; claims P,X WO, A 9006986 (HENKEL) 1-4 28 June 1990 see the claims X EP, A, 0239195 (UNILEVER) '1,5,7,8,9 September 1987.. see page 8, line 10; claims *Special categories of cited documents: 10 'IT" tstet document published aftear the international filing date document difining the general state of the arn which In not oar priori'ty date and not in conflict with the application but considered to be of particular relevanca cited to understand the principle or theory underlying the invention e artier document but pubtished on or aftear the internatiorval document of particular retevance; the Claimed invention filin datecannot be considered novel or cannot be considered to document which may throw doubt, on priority claim(s) oi Involve an inventive step which is citedeto establish the publication date of another document of particular relevance; the claimed invention Citation or othe t peciat reason (as spocified) cannot be considered to involve an inventive Step when the document referring to an oral disclosure, use. exhibition or document is combined with one or more other such docu- other means ments, such combination being obvious to a person skilled document publis2had prior to the international filing date but in the aot. later than the priolity date claimed document member of the same* potent family IV. CERIFACATIcIN_________ Date of the Actual Completion of the International Search Dale of Mailing of this International Search Report 7th June 1991 129. k8 91 International Searchirig Authority Sg a of AJI~lbeVr Officer EUROPEAN PATENT OFFICEI Form PCTIISA210 (second sheet) Ijanuary t985) ANNEX TO THE INTERNATIONAL SEARCH REPORT ON INTERNATIONAL PATENT APPLICATION NO. EP 9100258 SA 44264 This annex lists the patent family members relating to the patent documents cited in the above-mentioned international search report. The members are as contained in the European Patent Office EDP file on 07/08/91 The European Patent Office is in no way liable for these particulars which are merely given for the purpose of information. Patent document Publication Patent family Publication cited in search report date member(s) date EP-A- 0346994 20-12-89 AU-A- 3626789 14-12-89 AU-A- 3626989 14-12-89 AU-A- 3632989 14-12-89 EP-A- 0346993 20-12-89 EP-A- 0346995 20-12-89 JP-A- 2034699 05-02-90 JP-A- 2034700 05-02-90 JP-A- 2038500 07-02-90 EP-A- 0368575 16-05-90 AU-A- 4461089 17-05-90 JP-A- 2189397 25-07-90 EP-A- 0359308 21-03-90 AU-A- 4146589 22-03-90 JP-A- 2133498 22-05-90 WO-A- 9006986 28-06-90 OE-A- 3842007 21-06-90 EP-A- 0373483 20-06-90 EP-A- 0239195 30-09-87 None EP-A- 0346995 20-12-89 AU-A- 3626789 14-12-89 ALI-A- 3626989 14-12-89 AU-A- 3632989 14-12-89 EP-A- 0346993 20-12-89 EP-A- 0346994 20-12-89 JP-A- 2034699 05-02-90 JP-A- 2034700 05-02-90 JP-A- 2038500 07-02-90 FR-A- 2396114 26-01-79 DE-A- 2828416 18-01-79 SFor more details about this annex se Omicial Journal o~ te European Patent Ofce, No. 12/82

.4 For more details about this annex see Official Journal 6f thef European Patent Office, ,No. a;2/82