AU675648B2 - Method for cleaning aluminum at low temperatures - Google Patents

Description

OPI DATE 13/12/93 AOJP DATE 24/02/94 APPLN. ID 42376/93 PCT NUMBER PCT/US93/04316 I 1111111 11 11 11111 Illlll 11111111 111 II AU9342376 (51) International Patent Classification 5 International Publication Number: WO 93/23590 C23G 1/12 A (43) International Publication Date: 25 November 1993 (25.11.93) (21) International Application Number: PCT/US93/04316 (74) Agent: ORTIZ, Daniel, Henkel Corporation, 140 Germantown Pike, Suite 150, Plymouth Meeting, PA 19462 (22) International Filing Date: 12 May 1993 (12.05.93) (US).

Priority data: (81) Designated States: AU, BR, CA, JP, KR, NZ, US, Euro- PL 2410 14 May 1992 (14.05.92) AU pean patent (AT, BE, CH, DE, DK, ES, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE).

(71) Applicant (for all designated States except US): HENKEL CORPORATION [US/US]; 140 Germantown Pike, Published Suite 150, Plymouth Meeting, PA 19462 With international search report.

(72) Inventors; and Inventors/Applicants (for US only) BROWN, Malcolm, David [AU/AU]; 5 Mackintosh Road, Glen Waverley, VIC LAMBDEN, Shane, Peter [AU/AU]; 14 Hands Road, Kalorama, VIC (AU).

675648 (54)Title: METHOD FOR CLEANING ALUMINUM AT LOW TEMPERATURES (57) Abstract An acidic cleaning process for aluminum, especially aluminum cans, that includes a pre-cleaning washing stage followed by an acid cleaning stage is improved by including in the pre-cleaning washing solution both of a component of polyalkoxylated straight or branched chain alcohol surfactant and (ii) a component of polyalkylene glycol-abietic acid surfactant, which are maintained during the process in a ratio of component to component (ii) within the range from 0.4:1 to 3.0:1. The method is particularly useful when the acid cleaning stage also contains both these types of surfactants, but at a lower ratio. A pre-cleaner replenisher composition comprising water, sulfuric acid, and polyalkoxylated straight or branched chain alcohol surfactant is advantageously used in the process.

"I I WO 93/23590 PCT/US93/04316 Description METHOD FOR CLEANING ALUMINUM AT LOW TEMPERATURES Technical Field This invention relates to the cleaning of aluminum surfaces. In particular, it is directed to the cleaning of the surfaces of aluminum cans formed by a cold forming operation.

Background Art After can formation by cold forming, aluminum fines, lubricating oils and other contaminants remain on the surface. It is necessay to clean the surface thoroughly prior to the further treatment which often includes the application of one or more surface coatings.

Early cleaning compositions for aluminum surfaces proposed the use of aqueous acidic compositions either alone or with added fluoride at temperatures in the range of 185 to 200 o F (85 to 93 0 In United States patent 4,009,115 and its Re-Issue No. 32,661, Binns proposed the addition of 0.05 to 0.1 grams per liter of hydrofluoric acid as a means of reducing the processing temperature to within the range of 90 to 135 F (32 to 57 The compositions proposed by Binns preferably contain 0.1 to 10 grams per liter of a surfactant which could be anionic, cationic or nonionic.

King et al. in United States patent specification 3,969,135 proposed the use of an aqueous acidic cleaning composition containing a blend of two surfactants. This composition was also suitable for relatively low temperature use and preferably contained 0.01 to 0.4 weight percent of a fluoride accelerator. The surfactants proposed by King et al. (hereinafter abbreviated as simply "King") were a polyalkoxylated straight chain alcohol and a polyalkylene glycol-abietic acid surfactant. The King compositions are currently used in one or more, preferably at least two, cleaning stages in the commercial production of aluminum cans, but not usually in the first stage. Normal current practice is to provide most of the acidity in the precleaning stage, immediately before washing the cans with a cleaner composition as taught by King, by directing part of the acid cleaner washing solution into the pre-cleaner washing solution, which otherwise consists largely of tap water, with optional additions WO~O 93/23590 PCT/US93/04316 of acid. When a second stage acid washing solution as taught by King is used in this manner, the ratio between the two kinds of surfactants normally will be the same in the first stage as in the second, if nothing else is added to the first stage solution, inasmuch as no preferential dragout of one type of surfactant has been observed.

Washing operations with solutions that include nonionic surfactants are normally conducted at or slightly below the cloud point of the washing solution, which is the temperature at which the surfactant comes out of or goes into aqueous solution with changing temperature. It is a characteristic of most nonionic surfactants, including those taught by King as noted above, that they become less soluble in water as the temperature of an aqueous surfactant composition is raised. At temperatures significantly below the cloud point of a particular composition, foaming of the aqueous solution generally occurs quite easily, and it is desirable to avoid foaming in the present washing operations. If the temperature of the composition is too far above the cloud point, separation of the surfactant from the aqueous medium occurs and leads to a loss of detergent aliiity and a loss of the actual surfactant material.

Accordingly, the present washing operations are normally conducted at or below the cloud point where the detergent ability of the composition is still effective and foaming can be minimized.

Disclosure of the Invention Problems to Be Solved by the Invention While the methods described above are effective in cleaning the aluminum surfaces, removal of oil from the used washing solutions is necessary to prevent environmental pollution upon discharge of the used solutions. It is therefore an object of the present invention to provide a method which will not only be cost effective but will also allow an easier separation from the used washing solution of the oil which that solution has removed from the washed surface. Another object of the present invention is to provide a method of cleaning surfaces which will use the improved cleaning method in conjunction with the composition and equipment of the kind currently used in the production of aluminum cans. Still another object of the invention is to provide a process for satisfactory cleaning at a lower temperature than prior art processes, thereby making more economical operation possible. Other objects will be apparent from the description below.

2A Throughout the description and claims of this specification, the word "comprise" and variations of the word, such as "comprising" and 'comprises", is not intended to exclude other additives or components or integers.

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WO 93/23590 PCT/US93/04316 Summary of the Invention In one of its major embodiments, the present invention is based on the discovery that the ratio of the concentration of polyalkoxylated alcohol surfactant to the concentration of polyalkylene glycol-abietic acid surfactant (this ratio being s hereinafter briefly denoted "the surfactant ratio") that is optimum for the acid cleaner stage as taught in the King patent already noted above is not usually optimum for the pre-cleaning stage used immediately before the acid cleaner. In addition, independently, it has been discovered that the acid composition normally used in an acid cleaning solution as taught by King can usefully be supplemented with additional 1o sulfuric acid for the pre-cleaner stage. Accordingly, one embodiment of the invention is the provision of a prewashing solution composition with these improved characteristics before, preferably immediately before, a conventional acid cleaning solution in a cleaning operation with at least two stages.

Both these improvements in the pre-cleaner solution can conveniently be 1i achieved by adding to it during the course of the washing process a replenisher composition that comprises, more preferably consists essentially of, or still more preferably consists of water, sulfuric acid, and a polyalkoxylated straight or branched, but preferably straight, chain alcohol surfactant. The content of sulfuric acid in the replenisher composition is preferably determined by the pH required in use of the composition, and the content of surfactant is adjusted to maintain the stability of the composition. In particular, the composition may contain 5 to 50 per cent by weight of sulfuric acid and 0.5 to 40 per cent by weight of said surfactant.

In the method of one embodiment of the invention, such a composition is added to a washing solution as a replenisher composition in a stage preceding, preferably immediately preceding, a conventional acid cleaner stage, such as is taught by Binns or King. The use of such a composition as a replenisher is another aspect of the present invention.

Detailed Description of the invention The pre-cleaner stage of a process according to one embodiment of this invention preferably contains both of a component of polyalkoxylated straight or branched chain, preferably straight chain, alcohol surfactant and (ii) a component of polyalkylene glycol-abietic acid surfactant as taught by King. However, the ratio be- WOr 93/23590 PCT/US93/04316 tween these two types in the pre-cleaner stage of a process according to this invention preferably is within the range from 0.4:1 to 3.0:1, more preferably within the range from 0.7:1 to 2.0:1, still more preferably within the range from 0.9:1.0 to 1.3:1.0, and most preferably within the range from 1.0:1.0 to 1.2:1.0. (In contrast, the most preferred range for the second acid cleaner stage as taught by King, and as preferably used as the next subsequent process in this invention, after the pre-cleaner stage as described above, is about 0.3) Independently, the pH of the pre-cleaning solution in a process according to this invention is preferably within the range from 1.4 to more preferably within the range from 1.6 to 2.0, or still more preferably within the range from 1.75 to 1.85, and this pH is preferably achieved by adding to the water used for the pre-cleaning solution only sulfuric acid, in addition to whatever acid is added by countercurrent flow from the subsequent cleaner stage solution.

In a preferred embodiment, the values as described above for the pre-cleaner stage solution are achieved by adding to the original solution during the continued operation of the process a pre-cleaner replenisher composition, in addition to a counterflow from the subsequent acid cleaner solution stage. A pre-cleaner replenisher composition for the present invention comprises, more preferably consists essentially of, or still more preferably consists of, a stable aqueous solution of sulfuric acid with a polyalkoxylated straight or branched chain alcohol surfactant.

This improved composition is formulated to be used as a replenisher for the precleaner washing solution which is actually applied to the aluminum surfaces. It may be used alone but is preferably formulated for use in co-operation with the type of composition proposed by King et al., using successive cleaning stages in the can washing equipment. The relative concentration of the components in the composition of the present invention will preferably depend upon the type of system in which the composition is to be used, that is whether the composition is to be used alone or in conjunction with one of the known cleaning compositions.

It has been found that a stable and satisfactory pre-cleaner replenisher composition in accordance with the present invention can be prepared containing 5 to 50 per cent by weight of sulfuric acid and 0.5 to 40 per cent by weight of surfactant.

Preferably, the composition contains 30 to 41 per cent by weight of sulfuric acid and 4 to 10 per cent by weight of surfactant; most preferably 41 per cent by weight of I 1 I WO 93/23590 PCT/US93/04316 sulfuric acid is used. The sulfuric acid content can be varied depending on the way in which the composition is to be used and any such variation will preferably be accompanied by a corresponding variation in the range of surfactant material present.

However, once the acid content has been determined, the surfactant content to provide an optimally stable and useful composition can also readily be determined.

The acid content may require variation depending upon the amount and type of material to be cleaned from the surfaces being treated. This will vary with the type of lubricant used in the can formation and with other factors such as the condition of the forming equipment.

Suitable polyalkoxylated straight or branched chain alcohol surfactants are known in the art as nonionic surfactants. They include those sold under the trade names Antarox LF 330, Teric 165 and Trycol LF 1. These surfactants are known to have a low cloud point and their use in the present compositions assists in further lowering the temperature at which the washing operation is conducted.

It has been found that the compositions of the present invention can be used to significantly lower the pH of the pre-cleaner washing solution in use from the value that it would have if acidified by counterflow from a subsequent acid cleaner stage alone. The reduction in pH which can be thus achieved has been found to improve the cleaning efficiency of the washing solution and the efficiency with which oil can removed.

In a preferred application of the present invention, the improved composition is used in the first of two stages of a washing operation, the second stage using either a known composition of the type proposed by King et al or a composition of this known type modified to co-operate with the composition of the present invention.

The following comparison example and example of this preferred use of the invention will further assist an understanding of the benefits which the invention provides.

Comparison Example In a can processing plant including a multi-stage washing section, cans leaving the body maker-trimmer operation section travel on a perforated mat through a precleaner washing stage (stage 1) and then through a cleaner stage (stage In accordance with the known washing procedure, washing solution is initially made up with the desired proportion of active ingredients. The composition of the washing so- I I WO 93/23590 PCT/US93/04336 lution is maintained by the addition of appropriate replenisher compositions to compensate for the depletion of active materials as the washing procedure continues. The washing solution is sprayed over the can surfaces in the second section and a portion of the washing composition, carrying aluminum, oils, and other materials removed from the can in stage 2, travels in countercurrent to the movement of the cans to stage 1.

In a typical operation using a composition of the type suggested by King et al, the washing solution used in the stage 2 process contains a polyalkylene glycol-abietic acid surfactant blended with a polyalkoxylated straight or branched chain alcohol. A 1o typical washing solution containing approximately 0.065 per cent of the abietic acid derivative sold under the trade designation Teric RA 1315 and approximately 0.023 per cent of the polyalkoxylated straight chain alcohol sold under the trade name Antarox LF 330, as well as sulfuric acid and hydrofluoric acid, provides eight points of free acid in stage 2 at a pH of approximately 1.2. The amount of surfactant blend 16 and acids used in accordance with this process may be varied to provide between 3 to 20 points of free acid.

The washing solution from stage 2 is counterflowed to stage 1 at a rate determined by measuring the amount of dissolved aluminum in the solution. The amount of sulfuric acid in the washing solution is depleted because the acid dissolves aluminum in the course of its cleaning action. The balance of active components in the acid cleaner washing solution is maintained, most preferably by the addition of appropriate amounts of a replenisher composition. (This replenisher composition for the acid cleaner will normally have different composition from the pre-cleaner replenisher that is part of this invention.) In a typical can washer, for a flow rate of washing solution from stage 2 to stage 1 of five liters per minute, the amount of active acid cleaner replenisher composition is approximately 65 milliliters per minute. The r, e-oat which the washing solution from stage 2 is added to the stage 1 washing process is also controlled to determine the amount of free acid remaining in the washing solution used in precleaner stage 1. If the acid washing solution is added to stage 1 to provide one point of free acid, the pH is approximately 2.1. If two points of free acid are added by the stage 2 washing solution to stage 1, the pH is approximately 1.8.

I I WO 93/23590 PCT/US93/04316 Example According to the Present Invention The known process described above can be improved by using a pre-cleaner replenisher composition according to the present invention. Thus a pre-cleaner replenisher composition as described above can be added to stage 1 to supplement the 6 free acid content of the total washing solution in this stage. For example, if approximately one point of free acid in stage 1 is contributed by the counterflow of the washing solution from stage 2, and approximately one point of free acid is contributed by a preferred pre-cleaner replenisher composition for the present invention, the additional polyalkoxylated straight or branched chain alcohol added by 1o the composition of the present invention changes the ratio of the concentration of polyalkoxylated alcohol surfactant to the concentration of polyalkylene glycol-abietic acid surfactant ("the surfactant ratio") from approximately 0.3 to approximately 1.1, thus significantly lowering the cloud point of the stage 1 washing solution. This addition also alters the pH from approximately 2.1 to approximately 1.8.

is It has been found that changing the surfactant ratio, by the addition of polyalkoxylated straight or branched chain alcohol surfactant, to the stage 1 washing solution can lead to a reduction of approximately 10 C in the cloud point. The extent to which the cloud point is lowered will directly influence the extent to which oil is separated from the washing solution.

Based on the use of approximately 65 milliliters of active replenisher composition per minute in the counterflowed stage 2 washing solution being required to maintain one point free acid in thl stage one process, the amount of pre-cleaner replenisher composition according to the present invention required would be approximately 32 milliliters per minute or 50 liters per day.

Use of an improved pre-cleaner replenishing composition of the invention as described in the preceding example can be modified in accordance with the required flow rates necessary to achieve efficient cleaning of the particular cans being processed and more efficient oil removal from the washing solution. In addition, the composition of the (generally different) replenisher solution added to the stage 2 cleaning process can be varied to take into account the effect of the improved cleaning achieved in the stage 1 process by use of the cleaning composition of the present invention. The composition of the replenisher added to the stage 2 processing WO 93/23590 PCT/US93/04316 may also be varied to allow for the effect, on the concentrations and ratios of its active materials, of the materials which may be carrie.. over into the stage 2 process, by the cans moving from stage 1, when an improved composition according to this invention is used for the washing solution in pre-cleaner stage 1.

Claims (15)

1. A can washing process comprising passing initially soiled aluminum cans through an acidic pre-cleaner washing stage which uses a washing solution that comprises both of a component of polyalkoxylated straight or branched chain alcohol surfactant and (ii) a component of polyalkylene glycol-abietic acid surfactant, and through a subsequent acid cleaner stage, characterized in that the surfactant ratio of component to component (ii) in the washing solution in the pro cleaner washing stage is within the range from 0.4:1 to 3.0:1 and is different from the ratio if any of component to component (ii) in the washing solution used in the subsequent acid cleaner stage, and in that the surfactant ratio of component to component (ii) in the washing solution used in the pre-cleaner washing stage is maintained during the course of the process within the range from 0.4:1 to by addition of a replenisher solution 15 that consists essentially of water, sulfuric acid, and a polyalkoxylated straight chain alcohol surfactant to the washing solution used in the pre-cleaner stage.

2. A process according to claim 1, wherein the surfactant ratio of component to component (ii) is within the range from 0.7:1 to 2.0:1.

3. A process according to claim 2, wherein the surfactant ratio of component to component (ii) is within the range from 0.9:1.0 to 1.3:1.0, and component (i) Sis selected from polyalkoxylated straight chain alcohols.

4. A process according to claim 3, wherein the pH of the washing solution in the pre-cleaner washing stage is maintained during the course of the process within the range from 1.75 to 1.85. A process according to claim 2, wherein the pH- of the washing solution in the pre-cleaner washing stage is maintained during the course of the process wihtin the range from 1.6 to JJ C\WINWORDUACKIElNODELETEM42376N93.DOC

6. A process according to claim 1, wherein the pH of the washing solution in the pre-cleaner washing stage is maintained during the course of the process within the range from 1.4 to

7. A process according to any one of claims 1 to 6, wherein the washing solution for the acid cleaner stage comprises both of a component of polyalkoxylated straight or branched chain alcohol surfactant and (ii) a component of polyalkylene glycol-abietic acid surfactant, which are maintained during the course of the process in a surfactant ratio of component to component (ii) less than 0.4:1; during the course of the process, a portion of the washing solution from the acid cleaner stage is countercurrently introduced into the pre-cleaner washing solution; and during the course of the process, a pre-cleaner replenisher composition comprising water, slfuric acid, and a component of polyalkoxylated straight or branched chain alcohol surfactant is also introduced into the pre- 15 cleaner washing solution.

8. A process according to claim 7, wherein the pre-cleaner replenisher c-'mposition contains 5 to 50 per cent by weight of sulfuric acid and 0.5 to 4L per cent by weight of surfactant.

9. A process according to claim 8, wherein the pre-cleaner replen'rner composition contains 30 to 41 per cent by weight of sulfuric acid and 4 to 10 per Scent by weight of surfactant.

10. The use of a stable aqueous solution comprising water, sulfuric acid, and a component of polyalkoxylated straight or branched chain alcohol surfactant as a pre-cleaner replenisher composition to lower to pH of a washing solution in a pre- cleaning stage of a washing process containing at least two stages, including an acid cleaning ctage following said pre-cleaning stage, said washing solution in the pre-cleaning stage comprising both of a component of polyalkoxylated straight or branched chain surfactant, and (ii) a component of polyalkylene glycol-abietic acid surfactant, in a surfactant ratio of from 0.4:1 to 3:1, wherein the ratio of II I R :IE El ETE 7 9 DOC 11 component to component (ii) in the washing solution in the pre-cleaning stage is different from the ratio if any of component component (ii) in the acid cleaning stage for cleaning initially soiled aluminum cans.

11. A use according to claim 10, wherein the pre-cleaner replenisher composition contains 5 to 50 per cent by weight of sulfuric acid, and 0.5 to 40 per cent by weight of surfactant.

12. A use according to claim 11, wherein the pre-cleaner replenisher composition contains 30 to 41 per cent by weight of sulfuric acid and 4 to 10 per cent by weight of surfactant.

13. A process according to claim 1 substantially as hereinbefore described with reference to the Example. DATED 6 December 1996 PHILLIPS ORMONDE FITZPATRICK Attorneys for: 20 HENKEL CORPORATION J1 C.:WINVORD\JACKlE1NODELET342376N93.DOC INTERNATIONAL SEARCH REPORT Iteirnatial Appkatlon No PCT/US 93/043 16 .LASSIFICATION OF SUIJECT MATTER (If severaldaslficalon syabos appy, indicate all) 6 According to lotuitsulooal Patent Clssfflcztou (IPC) or to both National Cassficahion and IPC Int.Cl. 5 C23G1/12 EL FIELDS SEARCHED Minimum Documentation Searchedl Classification system Casfication Symbols Int.Cl. 5 C23G Documentation Searched other than Minimum Docmuentatioo to the Extent that such Documents are Included in the Fields Searche IL DOCUMENTS CONSIDERE TOBE RELEVANT 9 Category. Citation of Document, It with indication, where appropriate, of the relevant passges Z Relevnt to Claim No'l X GB,A,2 121 073 (PYRENE CHEMICAL SERVICES) 1-3,10 14 December 1983 see claims 1,15-20,22-26; example 1 X GB,A,2 100 757 (AMCHEM PRODUCTS) 1-3,7-12 6 January 1983 see claims 1,19,24; example 1 X GB,A,2 098 630 (AMCHEM PRODUCTS) 1-6, 24 November 3982 10-12 see page 5, line 5 page 5, line 21 see page 7; examples 7c,7d X EP,A,0 043 164 (METALLGESELLSCHAFT AG) 10-12 6 January 1982 see claims S pedal categories of cited documets 10 Tr Later document published after the international filing date defining o thpeealsaeriteatwic sntorit date and not In conflict with the aplication but document dfnnthgeeasttofteiwicIsotcited to understand the principle or theory unuaerlying the considered to be of partlilar relevanc inveton IV' earlier document but published on or after the internatinal 'IC document ofptcular releance; the claimed invention filing date cannot be co gdee anvl Or canno e considerud to L document which may throw doubts on rIty das or nvlv an inventive step which is cited to etbih th -eieln aeO aohry document of particular rilevance, the claimed Invention citation or other speia remLias ei cnot be considered to involve an Invenitive step when the document refosing to an oral disclosure, use, exhibition or document is combined with oue or am other such docu- other means ments, sech combination being obvous to a pawn skilled document published prior to the International filing date but in the art latr then th priority date claimed W document member of ths same "aet family IV. CERTIFICATION Date of the Actual Completion of the International South Date of Maling of this International Search Report AUGUST 1993 0 1. 09. s International Searching Authority Sipatze of Authorize Officer EUROPEAN PATENT OFFCE TORES F.M. Farn PCTIISA4IO (and shod) tJoina I NIS) litwuoW aAppllalcMNo PCT/US 93/04316 Ill. DOCUMETS CONSIDERED TO ISE RELEVANT (CONMlUE) FROM THE SECOND SHEET Catemy Maulim of Doamet, with LdMcaion, where a~ropdate, of the relevnt passag" Radevnt to Caim No. X US,A,4 124 407 (BINNS R. 10-12 7 November 1978 see column 7, line 53 column 8, line 22 A US,A,3 969 135 (KING P. F.) 13 July 1976 cited in the application A EPIA,O 157 382 (PARKER CHEMICAL COMPANY) 9 October 1985 A FR,AI,2 340 380 (SOCIETE CONTINENTALE PARKER) 2 September 1977 I J F.m PCTIISAIZIO 4~ra shi) tJin, IUS) f I I ANNEX TO THE INTERNATIONAL SEARCH REPORT ON INTERNATIONAL PATENT APPLICATION NO. us SA 9304316 73863 Thzs annex fists the patent fatnily menmbern relating to the patent doaiments cited in the abovv,-matoned international march report The memr are as contained in the European Patent Oftice EDP fie on The Euopean Patent Office is in no way Liable for them partiduaru which are merely gien for the pwposm of iforuzliaa 20/08/93 Patent document j Pulication Patent fam*l Pulication cited in search report dals nmamber(s) I date GB-A-2121073 14-12-83 AU-B- 553134 03-07-86 CA-A- 1207218 08-07-86 JP-A- 58185781 29-10-83 GB-A-2100757 06-01-83 US-A- 4435223 06-03-84 AT-B- 377539 25-03-85 AU-A- 8510682 06-01-83 BE-A- 893614 18-10-82 CA-A- 1182389 12-02-85 OE-A- 3223603 13-01-83 FR-A- 2508481 31-12-82 JP-A- 58006981 14-01-83 NL-A- 8202516 17-01-83 SE-A- 8203902 23-06-82 US-A- 4668421 26-05-87 GB-A-2098630 24-11-82 AU-B- AU-A- BE-A- CA-A- CH-A- DE-A, C FR-A, B JP-c- JP-B- JP-A- NL-A- SE-B- SE-A- US-A- 551181 8372482 893183 1180644 650276 3218054 2505862 1688547 3052550 57194264 8201978 448746 8203042 4370173

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30-08-82 08-01-85 15-07-85 02-12-82 19-11-82 11-08-92 12-08-91 29-11-82 01-12-82 16-03-87 16-11-82 25-01-83 EP-A-0043164 06-01-82 US-A- 4348294 07-09-82 AU-B- 530682 28-07-83 AU-A- 7218581 07-01-82 CA-A- 1151049 02-08-83 JP-C- 1205912 11-05-84 JP-A- 57051269 26-03-82 JP-B- 58038514 23-08-83 US-A-4124407 07-11-78 US-A- 4009115 22-02-77 'W F~r more details abotl this nm w Offiia jowual of the EuropeAn Patent Office, No. 12/82 4 I ANNEX TO THE INTERNATIONAL SEARCH REPORT ON INTERNATIONAL PATENT APPLICATION NO. 9304316 73863 This annex lists the paet fua~y members relat i to the ptct documnts dWe kn the above~metioned intermuioa mearch report The members m as contained in the European Patent Office EDP fil n The European Patent Office, is in no way liable for these particuam which am socrey given for the purpose of informaion. 20/08/93 Page 2 PtndouetPublicto )?stem atdy Publication ated in March report dot eiuu dates US-A-3969 135 13-07-76 AU-B- AU-A- CA-A- "P-C- JP-A- JP-B- 503941 1072976 1054497 1032206 51105928 53047289 27-09-79 11-08-77 15-05-79 29-01-81 20-09-76 20-12-78 EP-A-0157382 09-10-85 AU-A- 4053385 10-10-85 CA-A- 1223182 23-06-87 DE-A- 3511514 10-10-85 DE-A- 3564293 15-09-88 GB-A- 2157323 23- 10-85 FR-A-2340380 02-09-77 US-A- 4111722 05-09-78 AU-B- 510866 17-07-80 AU-A- 2205677 17-08-78 BE-A- 851186 08-08-77 CA-A- 1094430 27-01-81 DE-A- 2700642 11-08-77 GB-A- 1504502 22-03-78 JP-A- 52128848 28-10-77 NL-A- 7614586 11-08-77 SE-A- 7701464 10-08-77 'W For more details about this onnex sewe Offiial Journal of the European Patent Office, No. 12/82