AU624357B2 - Cleaning agent and process - Google Patents

Description

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OPI DATE 25/08/89 AOJP DATE 2899/89 APPLN. ID 30349 89

PCT

PCT NUMBER PCT/EP89/00068 INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (51) International Patent Classification 4 (11) International Publication Number: WO 89/ 07130 CI1D 3/43, 3/04, 3/08 Al C1D 3/10 3/20 (43) International Publication Date: 10 August 1989 (10.08.89) (21) International Application Number: PCT/EP89/00068 (81) Designated States: AT (European patent), AU, BE (European patent), BR, CH (European patent), DE (Eu- (22) International Filing Date: 24 January 1989 (24.01.89) ropean patent) F FR Eu ropean patent), GB (Europeanpatefit, TI ropet ipatent), JP, KR, LU (European.:patefit), N.,Euro ~an patent), NO, SE (31) Priority Application Number: P 38 02 127.7 '(Europeanl pangt, Us (32) Priority Date: 26 January 1988 (26,01.88) Published L (33) Priority Country: DE With international search report, (-F)-Applicant-for-all-designated States-except US) PUTRA,o L *Stanislav4-Y-U/DEl- -Erbslihstr.- D-5650-Solingen- -19-(DE), (?1X72) Applicant and Inventor: KAISER, Hans-Gerd [DE/ DE]; Germanenstr. 44, D-5650 Solingen 1 (DE), (74) Agent: HEIBER, Margarita; Futterstr. 33, D-5600 Wuppertal 2 (DE), (54)Title: CLEANING AGENT AND PROCESS (57) Abstract The invention allows cleaning of poorly accessible machine parts, e.g. in the transport and/or moulding of materials in the pasty state by addition of one or more inorganic or organic solvent(s) and one or more inorganic or organic salt(s) which are soluble therein, preferably as a solution, to the material to be processed. The melting point of the salt(s) is above the processing temperature of the material. The boiling point of the solvent(s) is below the processing temperature of the material. The invention finds its application in the change over of material to be processed in plastic processing machines, such as, injection moulding machines, extruders and blow-moulding equipment by accelerating the removal of the previous substance from the plasticizer unit and the nozzle region; an analogous field of use is, e,g. in the operation of kneaders, i L I I 3L I

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PCT/EP89/00068 W089/07130 1 Cleaning process.

The present invention relates to a cleaning process for cleaning poorly accessible machine parts, such as in the transport and/or moulding of materials in the pasty state, in particular in combination with the changeover of the processed material. This principally involves the removal of moulding material residues on change- over to another material. Thus, the invention relates to a simplification of the changeover of the moulding material to be processed in plastics-processing machines, such as, for example, extruders, injection-moulding machines, and blow-moulding equipment by accelerating the removal of the previous substance from the plasticizer unit and the nozzle region; an analogous field of use is, for example, in the operation of kneaders.

S: ince long, a wide variety of different cleaning S agents is used in technical and household applications.

FR-A-2 593 187 relates to a degreasing agent for metal and plastics parts, the degreasing agent containing, apart from water and sodium metasilicate, glycol ethers and alkylbenzene sulfonates as active ingredients.

In US-A-3 367 878 a cleaning agent for removing asphalt, sodium and/or metallic soap greases, road dirt, forming and cutting oils, and aviation dirt from ferrous V s PCT/EP89/00068 W089/07130 1A and non-ferrous metal surfaces is claimed, the cleaning agent containing specific glycols (hexylene glycol, propylene glycol) as active ingredients together'with a specific organic chelating ingredient, namely the tetrasodium salt of ethylene diamine tetraacetic acid in combination with water and sodium salts.

A cleanser for removing lard and other grease at temperatures of about 65,6 0 C from ovens, cookers, pots and tiles is described in DE-A-2 300 744, This cleaner is a water-comprising compositin with ammonia, or an organic amine together with organic cleaning compounds, and specific organic amides. The inorganic material which is also present in the cleanser of DE-A-2 300 744 is, at least partly, an abrading agent.

In the production of defined mouldings from pasty *4*o materials, such as, for example, thermoplastics or g• uduroplastics, and also in the processing of other substances in the softened state, as tne melt or paste, the following has been experienced: in machine parts w*hich come into contact I with the viscous moulding material, for example the plasticizer unit and the nozzle in injection moulding, moulding material is retained. These residues are gradually goo* discharged on changeover and contaminate the subsequent eeoe•S WO 89/07130 PCT/EP89/00068 mouldings and result in mouldings which are unusable for aesthetic or physical reasons.

This problem occurs, for example, in the plastics-processing industry when the colour is changed within a series. The losses in time, energy and raw materials until products of perfect colour are achieved are considerable.

Thus, it can be expected that a throughput of 650 kg of ABS (acrylonitrile-butadiene-styrene) material will be needed until pure white mouldings are produced in the customary injection-moulding manufacture of parts weighing 350 g on changing the colour from a beige ABS material to a similar white material.

The cleaning process outlined above, i.e.

working with a new material until perfect mouldings are achieved, and discarding the unusable mouldings made of a mixed material, cannot be justified from economic (material and energy costs for unusable products) and disposal points of view (burden on dumps caused by unus4ble and substantially undecomposable mouldings, environmental pollution on incineration, poor opportunity for recycling due to the material mixture).

Disassembly and manual cleaning is likewise an expensive method. In order to circumvent this problem, a further method is known from the prior art.

Thir involves the introduction of abrasion particles, for example A1 2 0 3 in suspension with organic solvents. The abrasion particles are added to WO,89/Q7130 PC/EP89/o0o68 the feed hopper of the plasticator together with the solvent, usually an aromatic, and the starting material in granule, chip or other form. Due to the combined action of the organic solvent, which at least causes the material residues in the screw channel and in the nozzles to swell, thus simplifying removal, and the abrasive action of the abrasion particles, the amount of unusable mouldings made from a mixed material is significantly reduced due to the more rapid removal of residual substances.

However, cleaning agents of this type are not without problems from industrial safety and environmental points of view.

The transport, storage and handling of cleaning agents of this type are associated with risks due to the necessary presence of organic solvents, whose flammability and/or toxicity makes them potential hazards.

For reasons of labour and property protection, their handling is subject to official regulations (for example West German Flammable Liquids Regulations; Transport of Hazardous Materials Regulations; Chemicals Act; Hazardous Industrial Materials Regulations). Since it is necessary for vapours to escape when these subi 25 stances are warmed in the machine, the guide concentrations (MAC values) can easily be exceeded locally.

In addition, the amounts used are not inconsiderable. Depending on the dimensions of the machine

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PCT/EP89/00068 W089/07130 4 to be cleaned, 0.2 1 to 1.5 1 of suspension are employed per changeover. The stocks in the plant must be arranged appropriately, which means that there is a not inconsiderable long-term risk.

In addition, the low stability of the suspensions results in careful mixing being necessary before use if the desired degree of distribution in the starting material, and thus the desired action, are to be achieved.

The object of the present invention is therefore to provide a cleaning process which reliably and quickly helps to remove residues of the previously processed melt or pasty i.o plastics processing material, using only a small amount of the subsequent plastics processing material, it being possible to formulate a cleaning agent for the process which is easy to handle and produces no problems with respect to the danger of fire and toxicity.

This object is surprisingly achieved by the cleaning process according to the present invention, which process j .C cleans poorly accessible parts of plastics- processing S. machines including kneaders, extruders, plastics moulding machines, plastics injection-moulding machines, and plastics blow-moulding machines, which machines transport handle I fand/or process plastics processing materials in the melt or pasty state, for removal of residues of the plastics processing material upon changeover of the plastics processing material in the plastics-processing machines to I lll

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eo *o PCT/EP89/00068 W089/07130 4A a subsequent plastics processing material, characterized in that a cleaning agent which is relatively colourless and relatively inert and containing at least one organic or inorganic salt together with one or more polar inorganic and/or organic solvents which dissolve the salt or salts, is introduced into the plastics-processing machine together with the first batch of the subsequent plastics processing material, optionally as a solution, if desired with additive substances, such as surfactants, or organic solvents, or alkalinizing agents, or emulsifiers, or abrasion particles, the melting point of the inorganic or organic salt or salts being above the processing temperature of the subsequent plastics processing material, and the boiling point of the solvent or solvents being below the processing temperature of the subsequent plastics processing material.

In preferred embodiments of the cleaning proc ss according to the invention: the concentration of the salt or salts in the cleaning agent is at least 0.5% by weight, based on the total weight of the solution, and the salt concentration is up to the saturation limit at room temperature; or (ii) the concentration of the salt or salts in the cleaning agent is 5% by weight to 20% by weight, based on the total weight of the solution; or (iii) the cleaning agent solution has a pH in the range from 4 to 14, more preferably in the range from pH 8 to 11; or i PCT/EP89/00068 W089/07130 4B (iv) the boiling point of the solvent or solvents in the cleaning agent is at least 30 0 C below the processing temperature of the subsequent plastics moulding material; or the solvent in the cleaning agent is water.

In further preferred embodiments of the cleaning process according to the invention: (vi) the melting point of the salt or salts in the cleaning agent is at least 50 0 C above the processing temperature of the subsequent plastics moulding material; or (vii) the salt in the cleaning agent comprises alkali metal carbonate(s), alkali metal metasilicate(s), alkali metal tartrate(s), alkali metal acetate(s), or mixtures thereof; or (viii) the cleaning agent contains 10% by weight of 15 alkali metal carbonate and/or alkali metal metasilicate, i:.6 based on the total weight of the cleaning agent; or 0 (ix) the cleaning agent contains abrasion particles, or S: alkalinizing agents, or non-polar organic solvents, or emulsifiers, or surfactants, or other such additives.

20 As shown in the working example, the cleaning agent used in the process of the invention is highly efficient. Material changeovers which otherwise require several hours and produce a large amount of rejects can be carried out within a few minutes. It must also be realised that H20 can be used as a solvent which WO 89/67130 PCT/EP89/00068 .5 presentz; absolutely no toxicological probl.ems in humans or the environment. As far as salts which are suitab]',e with respect to the melting points are concerned, there isasufficiently large choice of substances, known to any chemist, which are not hazardous materials. Most of the plastics -processing processes which are important here operate at temperp.tures between 100 and 200 0 C. It a-rises from the objective that the salts, solvents and all 'the additives must be colour-less and inert at the processing temperature of subsequent material.

since the organic and/or inorganic salt, which is the active substance in accordance with the invention, is in the form of a solution, homogeneity is ensured. Sepa-ration, with suibsequent distribution pr-oblems in the granules, I.e. a poor cleaning action, cannot occur.

With respect to homogeneous dispersion in the material for plastif~ication, however, addition, of sufac*,an-I- so that thQ surface tenzion betwen the particular plastic and the cleaning solution is reduced proves expedient in the p.-ocess and agent according to 0 the invention.

the cleaning process and agent of the invention are not limited to certain typos at material or certain :25 combinations of sucCessive substances. Examples which may be mentioned are: a. a a a.

a a o e 00040 0..

1 WO 89/07130 PCT/EP89/00068 ABS, AMMA, CA, DPA, EP, EVA, EVAL, HDPE, LDPE, MBS, PA, PC, PMMA, PS, PVC, POM, PPR, PBT, SAN and UF. The moulding materials may be filled or unfilled.

With regard to the reduction of the danger of corrosion of metallic machine parts, it proves expedient to employ a cleaning solution having a pH of from 7 to 14. The use of a basic salt, such as, for example, Na 2

CO

3 or alternatively sodium metasilicate is appropriate due to the acid-neutralizing action, in particular when PVC or other acid-eliminating materials are used.

Although it is generally not necessary to use organic polar or non-polar solvents in the present invention, it may be expedient, in the case of residues which are particularly difficult to remove, to add organic solvents, if appropriate together with an emulsifier, to the cleaning solution. In these cases too, the amount of solvent employed is many times smaller than in the case of customary cleaning suspensions, S0 with the same cleaning action.

I The concentration of the salt in the cleaning I agent according to the invention can vary within broad limits. An activity lower limit for the concentration is at about 0.5% by weight. For reasons of easier handling during transport and storage and in order to limit the v6lume of liquid to be evaporated, higher concentrations are advisable as long as the viscosity :if WO'89/07130 PCT/EP89/00068 does not make discharge and distribution more diffi- I cult. However, it is of course possible to appropriately dilute a solution concentrated in this way "on site". In addition, salts and solvents can be kept separate before use. The actual cleaning solution is then prepared immediately before use by dissolving the solid salts. It is likewise possible to keep additives, for example alkalinizing agents such as NaOH, separate for storage and transport in the form of a "kit of parts" and only to add them when the solution is used.

The working example below illustrates the effectiveness of the procedure according to the invention: Example The following materials were processed under laboratory and production conditions, coloured pigments being used in batch, powder and liquid state: ABS, CA, HPDE, LPDE, PA, PA 6, PA 6.6, PA 11, PA 12, PC, :a PMMA, PPO, PPS, PS, soft PVC, SAN, PBT and PPR.

Most of the PA groups have been modified with short and long glass fibres and with glass beads up to and also with MoS (2 to 4 Experiments were carried out in the following injection-moulding machinest Arburg 221 75 350 Screws: 0 0 0 WO 89/07130 PCT/EP89/00068 Arburg 305 210 700 0 0 0 Arburg Eco 305 -700 230 0 0 Rico 110 0 0 I. Production of casings for automatic coffeemakers: Machine: 200 t Screw: 65 0 Mould: hot channel 1-fold Material: ABS colours Changeover from dark brown to beige: a) conventionally by introducing the subsequent material; it was necessary to twice disassemble the mould and carry out mechanical cleaning before the beige colour shade was satisfactory Material consumption: about 600 kg of ABS Time consumption: about 10 hours V b) using the cleaning agent according to the 1 invuntion (Na 2 CO 3, 10% strength by weight, in distilled H20; 0.03 kg) Material consumption: about 6 kg of ABS Time consumption: about 15 minutes 1 7 IO'8 19/ 1 '07130 PCT/EP89/00068 g The changeover was likewise completed in about minutes using sodium metasilicate (10% strength by weight in distilled H 2 0; 0.03 kg).

II. Production of disposable razors: Machine: 250 t Screw: 80 0 Mould: hot channel, 12-fold Material: high-impact PS colours on colour changeover a) conventionally without cleaning agent with multiple disassembly of the mould and mechanical cleaning in each case before the changeover was complete Material consumption: about 350 kg of PS Time consumption: about 24 hours Simple cleaning (orly the plasticizing unit) took about 10 minutes.

Vented screws were an exception. They could not be cleaned according to the invention in the pressurefree end region, but instead had to be subjected to manual cleaning.

i" PCT/EP89/00068 W089/07130 10 Comparative Tests The experiments set forth below were carried out with an Arburg 305/210/700 injection moulding machine, the diameter of the screw being 35 mm.

To corroborate the efficiency of the present invention, distilled water and tap water from the local drinking water supply network in Solingen were employed in experiments I, II below. Consumption of subsequent material and time necessary for achieving changeover in the production of solid articles made of polypropylene was determined until immaculate articles of the subsequent material could be achieved, f* Experiments III, IV, V, as described below were carried out in accordance with the present invention employing inorganic salts as well as organic salts with inorganic or organic solvents demonstrating the technical effect of the invention.

Polypropylene (PP) was used in these tests, and changeover was carried out from PP black to PP undyed. Pressure plates were manufactured by injection moulding. The temperature in the cylinder was 200'C 210°C.

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'F U~ i c_ i~ PCT/EP89/00068 W089/07130 11 Experiment I: 1kg PP undyed was mixed with 1% weight distilled water With this mixture it was attempted to change over from PP black to PP undyed. Directly after emptying the cylinder by injecting, the mixture was inserted subsequent to the PP black and the manufacturing process was continued with PP undyed without addition of any further additive. Result: Even after two hours, black inclusions still showed in the injection moulded articles thus manufactured.

Experiment II: This experiment was carried out in the same manner as experiment I, except that tap water from the supply network for drinking water in Solingen was employed instead of .*to distilled water. The experimental result was identical to that of experiment I. Annotation: Blank experiments I and II were broken off after 2 hours, as no satisfactory cleaning could be achieved. The articles manufactured were not fit for sale because of inclusions consisting of the precursor.

material PP black were still present.

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If.: PCT/EP89/00068 W089/07130 12 Experiment III: g Potassium acetate were dissolved in 19 g ethyl alcohol.

g of this solution were mixed with 1 kg granules of PP undyed. 280 g of this mixture were inserted immediately after the cylinder was cleaned by injection moulding from precursor product PP black. After that, PP undyed was employed without any further additives. After injection moulding of three articles (dump articles with black inclusions), all residues were eliminated, After cleaning the machine of the above 280 g mixture by injection moulding, immaculate articles consisting of PP undyed could be produced immediately. Time consumption of this cleaning was about 2.5-3 minutes.

9* 9* 9 9 9 4 4I 9* A 44 .9i~ 9 Experiment IV: g sodium acetate were dissolved in 80 g ethyl alcohol 10g of this solution were mixed with 1 kg PP undyed.

240 g of this mixture were brought into the cylinder immediately after the precursor product PP black had been cleaned out by injection moulding, After injection moulding of three articles, all residues were eliminated, After that, PP undyed was employed without addition of any further additive, After cleaning the machine of these 240 g mixture by injection moulding, immaculate articles of PP undyed could be produced immediately. Time consumption for this cleaning method was about 2 minutes.

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W089/07130 13 PCT/EP89/00068 ExT)eriment V: g potassium chloride were dissolved in 80 g distilled water. 10 g of this solution were mixed with I kg PP undyed.

210 g of this mixture were inserred immediately after the precursor product PP black, (after that, PP undyed was employed without addition of any further additive). After an injection sequence of three articles, all residues were eliminated. After clearin4 out these 210 g mixture by injection moulding, immaculate articles consisting of PP undyed could be produced. Time consumption of this cleaning method was about 1.5-2 minutes.

The results of Experiments I-V are summarized in the table: f ollowing 0%

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ccMposition of salt solution material (mixture) amount of mixture used in cleaning time con- result of sumption cleaning/ quality of articles Experi men t 1: 1 kg PP undyed I kg 2 h unfit for 10 g dist. use/still contamination of PP black Experiment ii: i kg PP =dyed I kg 2 h as for 10 g tap water Experiment I Experiment III: Experiment IV: 1 kg PF undyed 10 g potassium acetate dissolved in 90 g ethyl alcohol I kg PP undyed 20 g sodium acetate dissolved in 80 g ethyl alcohol (20 vol.%) I kg PP undyed 20 kg potassium chloride dissolved in So g dist. 280 g 2.5- 3 min excellent/ articles of PP undyed without any contamination 2 min as for Experiment

III

240 g Experiment V:, 210 g 1. 5-2 min as for Experiment

III

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PCT/EP89/00068 W0 89 /07130 1 Annotation to Experiments III, IV/ V: After concluding these experiments, the machine was emptied by injection moulding. Subsequent inspection revealed that the plastification unit had not been corroded in any way by cleaning according to the present. invention.

Claims (10)

1. A process of cleaning poorly accessible parts of plastics-processing machines including kneaders, extruders, plastics moulding machines, plastics injection-moulding machines, and plastics blow-moulding machines, which machines transport handle and/or process plastics processing materials in the melt or pasty state, for removal of residues of the plastics processing material upon changeover of the plastics processing material in the plastics-processing machines to a subsequent plastics processing material, characterized in that a cleaning agent which is relatively colourless and relatively inert and containing at least one organic or inorganic salt together with one or more polar inorganic and/or organic solvents which dissolve the salt or salts, is introduced into the plastics-processing machine together with the first batch of the subsequent plastics processing material, optionally as a solution, if desired with additive substances, such as surfactants, or organic solvents, or alkalinizing agents, or emulsifiers, or abrasion particles, the melting point of 1the inorganic or organic salt or salts being above the processing temperature of the subsequent plastics processing material, and the boiling point of the solvent or solvents being below the processing temperature of the subsequent plastics processing material. /y I MEM" PCT/EP89/0006L W089/07130 16

2. A process according to Claim 1, characterized in that the concentration of the salt or salts in the cleaning agent is at least 0.5% by weight, based on the total weight of the solution, and the salt concentration is up to the saturation limit at room temperature.

3. A process according to Claim 2, characterized in that the concentration of the salt or salts in the cleaning agent is 5% by weight to 20% by weight, based on the total weight of the solution.

4. A process according to any one of Claims 1 to 3, characterized in that the cleaning agent has a pH in the Srange from 4 to 14, A process according to Claim 4, characterized in that the cleaning agent has a pH in the range from 8 to 11. S 6. A process according to any one of Claims 1 to 4i characterized in that the boiling point of the solvent or solvents in the clean ig agent is at least 30 0 C below the processing temperature of the subsequent plastics moulding i material.,

7. A process according to any one of claims 1 to 6, characterized in that the solvent in the cleaning agent is water. 0te* u6S*** NeTw h- i PCT/EP89/00068 WO89/07130 17

8. A process according to any one of Claims 1 to 7, characterized in that the melting point of the salt or salts in the cleaning agent is at least 50 0 C above the processing temperature of the subsequent plastics moulding material.

9. A process according to any one of Claims 1 to 8, characterized in that the salt in the cleaning agent comprises alkali metal carbonate(s), alkali metal metasilicate(s), alkali metal tartrate(s), alkali metal 16 acetate(s), or mixtures thereof. A process according to Claim 9, characterized in that the cleaning agent contains 10% by weight of alkali metal carbonate and/or alkali metal metasilicate, based on the total weight of the cleaning agent. 15 11. A process according to any one of Claims 1 to characterized in that the cleaning agent contains abrasion S* *o* particles, or alkalinizing agents, or non-polar organic *e solvents, or emulsifiers, or surfactants, or other such additives, 20 12. A process according to Claim 1, substantially as described in the Example. DATED this 10th day of February, 1992 S HANS-GERD KAISER, By his Patent Attorneys, E. F. WELLINGTON CO., S. Wellington) ^T D/3325 j F INTERNATIONAL SEARCH REPORT Interniational Apolication No PCT/ EP 891/ 00068 I. CLASSIFICATION~ OF SUBJECT MATTER (if sevieal classific3iion symbols aopiy, indicate all) IAccording to Internationai Patent Classification (IPC) or to bothl National Classiication and IPC IC4. C 11 D 3/43; C 11 D 3/04; C 11 D 3/08; C 11 D 3/10; 11 D 3/20 1.FIELDS SEARCHED Mii~mDecumentation Searched 7 Classification Syatam jCiassification Symbols IPC 4C 11 D; C 08 F Documentation Searched other than Minimum Documentation to the Extent that such Documents are included in the Fields Searched III, DOCUMENTS CONSIDERED TO 5E RELEVANT'I Category *I Citation of Document! 11 with Indication, where appropriate, of the relevant Passages R Ielevant to Claim No, 11 Y FR, A, 2593187 MARON) 1-9 24 July 1987 see the whole document Y US, A, 3367878 MANKOVTC{) I1-9 6 February 1968 see the whole document Y DE, A, 2300744 (AMVERICAN HOME PROD,) 1-9 19 July 1973 see the whole document Y Chemical Abstracts, volume 99, no. 6, 1 August 1983, (Columbus, Ohio, US), see page 12, abstract 38980b, JP, A, 57147501 (GOODRICH, B.F., CO.) 11 September 1982 0 Speial categories of cited documnt,tIs To later document published after the International filing date iA* doeument defining the general state of the ert which le not orprlority dale and not in conflict with, the application but conldeed o b ofpaticlarreiyane ited to u~nderstand the principle or theory underlying the doumen butpublshedon o aftr thInntrnttonn tilealie doueI u ulse no fe h nentoa X" document of Particular relevancel the claimed Invention flng dae cannot be considered novel or cannot be consideried to document which may throw dioubats onxpiority claim(s) or Involve an Inventive, stop which Is cited to establish the publication date of another "Y document of particular reeancei' the claimed Invention Citation or other epoci#' reason (as epecifled) cannot be considered to Involve an Inventive step when the document ireferring to Wi oral disclosure, use, exhibition or document Is combined with one or more other such dOCu. other means .Monts, such combination being obvious to a person skilled 01P1 document Published Prior to he International flilng date but In the amt later then the priority date clainedl document member of the same patent family IV. CERTIFICATION_____________ Date of the Actu I Completion of the International Search Oale of M.ailing of this lInternlational Search Reoport 18th r~l 198923. CS 89 International Searching Authority I EUROPEAN PATENT OFFICE Form PCT/121 (secend shooet) (Januay 11114) Signature, of Athif~led OMfce i"I YAN PIOL ANNEX TO THE INTERNATIONAL SEARCIN REPORT ON INTERNATIONAL PATENT APPLICATION NO. EP 8900068 SA 26491 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 CDP file on 18/05/89 The European Patent Office is in no way' liable for these particulars which are mrnely given for the purpose of information, Ptutent document Publicatio Patent family Publilcation cited in search '-epnr! date member(s) date FR-A- 2593187 24-07-87 None US-A- 3367878 None DE-A- 2300744 19-07 -7 3 NL-A- US-A- BE-A- AT-B- AU-A- GB-A- AU-B- CA-A- CH-A- FR-A- JP-A- 7300288 3806460 793854 322701 5084773 1411032 468520 989696 584752 2331943 4808Q607

12-07-73

23-04-74 10-07-73 10-06-75 11-07 -74 22-10-75 15-01-76

25-05-76 1,5-02-77 10-06-77 9-10-73 'r w~ore details about this annex tsee official Journal of the Es0ropean Patent Office, No. 12/82 r