AU623169B2 - Compositions and methods for deodorizing toilet holding tanks - Google Patents

Description

i' ii OPI DATE 19/02/90 AOJP DATE 29/03/90

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APPLN. ID 40440 89 PCT NUMBER PCT/US89/03041 INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) International Patent Classification 4 A61L 2A 0 (11) International Publication Number: S(43) International Publication Date: WO 90/00906 8 February 1990 (08.02.90) (21) International Application Number: (22) International Filing Date: PCT/US89/03041 18 July 1989 (18.07.89) NL, NL (European patent), SE, SE (European patent).

Published With international search report.

Priority data: 221,286 19 July 1988 (19.07.88) (71) Applicant: THETFORD CORPORATION [US/US]; 7101 Jackson Road, Ann Arbor, MI 48103 (US).

(72) Inventor: BURROWS, Mary, R. 1810 Fair, Ann Arbor, MI 48103 (US).

(74) Agents: BRENNAN, Michael, P. et al.; Harness, Dickey Pierce, 5445 Corporate Drive, Troy, MI 48098 (US), (81) Designated States: AT (European patent), AU. BE (European patent), CH, CH (European patent), DE, DE (European patent). FR (European patent), GB (European patent), IT (European patent), LU (European patent), 823 16 (54)Title: COMPOSITIONS AND METHODS FOR DEODORIZING TOILET HOLDING TANKS (57) Abstract Compositions and methods of controlling the odor from a toilet system including a toilet tank comprise employing in said toilet tank an aqueous solution containing an effective amount of a polymeric material comprising a specific class of polyamides.

i F i -1 NVO 90/00906 PC'T/US89/0304 -1 COMPOSITIONS AND METHODS FOR DEODORIZING TOILET HOLDING TANKS BACKGROUND OF THE INVENTION This invention relates to deodorizing of humin waste-containing solutions in toilet systems. It is particularly useful in deodorizing such waste-containing systems in which the waste has to be stored in a toilet holding tank for prolonged periods prior to disposal.

In its preferred application, this invention relates to the deodorization prior to disposal of human waste in portable chemical field toilets, chemical or storage toilets as well as fresh water flush toilets associated with aircraft, buses, trailers, boats, recreational vehicles and the like, where waste-containing material must be stored or transported for extended periods of time.

As noted in U. S. 4,229,408, the prior art has attempted a wide variety of different approaches to the treatment and/or deodorization of human wastes or the like in chemical depositories over protracted intervals. The art-disclosed systems that have been developed for deodorization by the prior art have been satisfactory for short intervals of time because they have attempted to control odor by alleviating problems with bacterial growth and odor. As in 4,229,408, this has been done primarily by employing formaldehyde or formaldehyde-like anti-microbial or biocide materials, alone or in combination with other agents. However, recent developments in transportation and environmental regulation have precluded the random discharge of waste materials, particularly where the additives contained harmful and/or non-biodegradable material such as WO 90/00906 PCT/US89/03041 2 formaldehyde or formaldehyde-like materials or heavy metal products.

For example, U. S. Patent No. 3,653,499 relates to a storable stable paraformaldehyde sterilizing composition including a metal tripolyphosphate and a pH between 10 and 11, as well as other ingredients.

U. S. Patent No. 4,043,911, describes sterilization of holding tanks and like by quaternary compounds at a pH of 9-11 or higher.

U. S. Patent No. 3,883,303 describes the method for controlling odors in recirculating toilets by including in the toilet a composition containing borax and paraformaldehyde in the amount of 100-5000 parts per million.

U. S. Patent No. 3,208,936 describes an antiseptic recirculating toilet composition employing water, isopropanol solution, of quaternary amine such as percent isopropanol solution of l-(2-hydroxy-ehyl) 2-n-alkyl-lbenzyl-2-imidazolinium chloride in which the alkyl group is either oleic acid 29-54 linoleic acid and 46-61 percent oleic acid mixture or stripped coco fatty acids along with a myriad of other compositions; included in such systems is an acid selected from acetic and lactic to buffer the composition to a pH of approximately formaldehyde, Methyl Violet and Alizarin Blue Sapphire G dye, stabilizing agent, an indicating dye selected from a group beta methyl umbelliferone and soluble fluorescein, disodium phosphate and an odor masking agent, such as cashmere oil or musk oil.

U. S. Patent No. 2,998,390 describes a recirculating toilet sump fluid in which quaternary ammonium salts such as p-diisobutyl phenoxy ethoxy ethyl dimethyl benzyl ammonium chloride monohydrate are employed in conjunction with boric acid and the like to buffer the material to a pH of about 5 to prevent precipitation.

il_--1LIIIII~ i ',WO 90/00906 PCT/US89/03041 3 U. S. Patent No. 4,022,911 describes a disinfectant composition comprising a quaternary ammonium compound, a phenol and formaldehyde for killing bacteria.

U. S. Patent No. 3,941,696 describes sterilization of holding tanks by quaternary compounds at a pH of 9-11 or higher.

U. S. Patent No. 4,010,277 describes a synergistic composition containing polyoxyethylene sorbitol hexaoleate having about 40 oxy-ethylene groups for controlling growth of slime in cooling water systems and effluent water treatment.

U. 3. Patent No. 3,892,846 describes an animal bedding material treated with hydroxamic acid or salt thereof to prevent the decomposition of urea and malodor accompanying such.

U. S. Patent No. 4,007,262 describes an odor control system for use in a chemical toilet in which a neutral or basic transition metal salt of an inorganic acid or a lower aliphatic organic monocarboxylic acid is dissolved in aqueous ammonia or aqueous solution of a strong water soluble organic amine that is subsequentially acidified with sufficient mono- or poly-functional carboxylate acid or other suitable acidic ligand to produce a transition coordination compound and buffer system having a pH in the range of about 6.5 to 7.

U. S. Patent No. 3,749,672 describes a stabilized solution of N-halo compounds in which stability is provided by the inclusion of a buffer to neutralize the effects of hypobromite, hypochlorite, or hypoiodite.

U. S. Patent No. 3,734,291 describes waste treatment systems in which a macerator macerates the waste and provides mechanical entrapment, as by filtration.

U. S. Patent No. 2,990,266 describes a method for controlling plant growth in which substantially equal molar portions of a lower mono-alkanolamine and paraformaldehyde are present in combination with benzene.

I W'O 90 /00906 PCT/US89/03041 4 U. S. Patent No. 3,903,259 describes a method of deodorizing diapers and human excretia with a chemical composition comprising an acidic material, antibacterial material, and a solvent selected from a specific group.

4,034,078 describes a synergistically effective composition of an enzyme such as protolytic enzyme and a ferrous salt composition.

3,881,008 describes a process for controlling slime with N-2-nitrobutyl-morpholine and N-alkyl-dimethyl-benzyl ammonium chloride.

U. S. Patent No. 3,459,852 describes a deodorizing treatment of aqueous solution comprising mixing a sulfide-active alpha, beta unsaturated aldehyde or ketone in an amount sufficient to form a sulfur-containing reaction product.

U. S. Patent No. 3,785,971 describes a waste treatment material for preserving refuse and waste material within a container comprising a mixture of paraformaldehyde, an alkali material, a masking agent, a colorant and a wetting agent.

U. S. Patent No. 3,350,652 describes the use of anti-microbial composition including silver, sodium hypochlorite, hydrogen peroxide and formaldehyde.

U. S. Patent No. 4,043,911 discloses the use of quaternary ammonium compounds for watewater sterlization.

U. S. Patent No. 4,107,312 discloses quaternary ammonium compounds as disinfectants in toilets.

U. S. Patent No. 4,111,679 refers to polyamine for controlling microbiological growth.

U. S. Patent No. 4,229,408 discloses quaternary ammonium compounds used to control odor in toilet holding tanks.

Mazon 150, a polyamine material preferred for use in the present invention, is typically employed in the art in the form of a cationic liquid; it is used primarily as a coagulant in well water clarification. It is used as a total or partial replacement for inorganic salts and I 1 WO 90/00906 PCT/US89/03041 such uses. Other principal art-disclosed uses involve the treatment of wastewater where a liquid-solid separation is needed. These include gravity settling, water clarification, air floatation and filtration.

More recently, state and federal environmental protection agencies and the like have begun to show more interest in regulating when and where discharging of waste-containing materials is permissible and when and where discharging is proscribed. Such federal and state agencies are also evaluating whether they will proscribe the use of certain of these art-disclosed or art-employed agents if discharging is to be done in certain locations.

Compliance with these regulations may require holding waste materials in a toilet system for a much longer period than heretofore was necessary while, at the same time, eliminating the use of some very effective agents, such as formaldehyde. This magnifies the need for various treatments, particularly odor control, by an agent that is efficacious for longer periods of time, and which is environmentally-acceptable and non-corrosive. This is true not only of buses, airplanes, boats, and the like, but also of recreational vehicles and field toilets.

Lastly, it should be noted that several designs of toilet systems are in use today. Virtually all, however, incorporate a type of holding tank where solid wastes are stored in contact with a treatment solution or medium until disposal. Accordingly, the holding tank is where the odors must be suppressed, and the treatment solution or medium contains the necessary agents. The art has felt, as noted in 4,229,408, that in order to accomplish this goal, a deodorant additive must perform certain activities, including eliminating subduing bacterial growth.

It has now been discovered that a certain class of polymer materials, heretofore unrecognized as possessing any deodorizing capability, can be employed in a treatment solution or medium at relatively low leve-lsto i

N

WO 90/00906 PCT/US89/03041 6 control the odor from a toilet tank irrespective of its anti-bacterial activity, or lack thereof.

SUMMARY OF THE INVENTION The present invention provides compositions and methods which can control odors in toilet systems and toilet holding tanks for an extended period. The compositions and methods of the present invention employ an effective amount of a polymer material comprising a polyamine polymer material. The polyamine has the following general formula.

R

(cH 2) iP OH I R n wherein A, B and C are integers from 0-2, R 1 and R 2 are independently selected from the group consisting of methyl, ethyl, propyl and isopropyl, and X- is an environmentally-acceptable anion; and further wherein A, n B, C and are such that the final polymeric material has an average molecular weight of from about 5,000 to about 250,000. In a highly preferred embodiment, the average molecular weight of the polymer material employed in the compositions and methods of the present invention is in the range of about 20,000 to about 30,000, and the polymer material is employed in the preferred use compositions and methods as an aqueous solution at about 0.005 to about percent of the polymer material, by weight of the final composition/holding tank solution. The preferred embodiments of the compositions and methods of the present invention may also optionally employ other additives or agents such as a surfactant, a fragrance, a thickener, a second deodorizing agent or odor-masking agent and/or a i i Imm NVO 90/00906 PCT/US89/03041 7 dye, all of which are preferably environmentally-acceptable.

In a highly preferred, embodiment, the final compositions and methods are substantially free of formaldehyde or formaldehyde derivatives.

The methods of the present invention comprise adding to a toilet system having a holding tank an effective amount of the polymer materials or compositions described above, alone or in combination with one or more of the optional agents or additives.

In another aspect of the present invention, a use concentrate additive composition is prepared which can be added to a toilet tank system, or can be used to replenish the level of deodorizer in a toilet system.

Such use concentrate or additive compositions or solutions may contain a correspondingly higher predetermined amount of the polymer or other additives or &,gents disclosed herein according to the size or type of the toilet system or toilet holding tank. For example, a 4oz. additive unit dosage may preferably employ about 5 to about 40, and more preferably about 5 to about 30 percent of the polymer by weight of the additive composition.

DETAILED DESCRIPTION OF THE INVENTION All percentages employed herein are by weight, unless otherwise indicated. By the term "environmentally-acceptable", as employed herein, is meant that solutions containing the material may ultimately be disposed of in a conventional manner.

It has now been surprisingly discovered that class of polyamine materials is highly efficacious even when employed in an aqueous treatment solution or medium at very low levels in controlling the odor from a toilet system that includes a holding tank that contains human waste. Compositions and methods employing these have the advantage of being non-toxic, environmentally-attractive and non-corrosive.

WO 90/00906 PCT/US89/0304 8 The efficacy of this polyamine polymer material allows it to replace, in whole or in part, other art-taught and commercially employed deodorizing agents or compositions which may be undesirable from an environmental, human safety, consumer handling, corrosiveness, length of action, or cost standpoint.

The art has historically attempted to control odors with anti-microbial or biocidal additives, as odors were thought to be associated with such activity. Thus, for example, typical deodorizing methodologies, as noted above, include employing materials which are added to control bacterial or other microbial growth which has been associated with the generation of unpleasant odors. The most commonly employed of these agents are formaldehyde, or formaldehyde-like materials or derivatives, which are used to inhibit the growth of/or totally eliminate bacteria or other micro-organisms; formaldehyde is also believed to be a deodorant independent of its biocidal properties.

Many other antimicrobial materials, such as quaternary ammonium salts, have been employed to control odors. Other art-disclosed systems have employed an agent to control the pH of the holding tank solution to assist these anti-microbial agents in controlling bacteria or microbial growth.

It has now been discovered that a select class of polymer materials can be employed at a very low level to effectively control odor emission from a toilet system over a long period of time irrespective of the biological activity in the tank or system.

Accordingly, the compositions and methods of the present invention employ an effective amount of a polymeric material comprising an aqueous solution of a polyamine having the following formula (formula A) L -I 8a

C~(H

2 )CC) r-n (CH, 2 )r"

AH

ft *Op n 9**

S

NOo 90/00906 PCT/US89/03041 9 wherein A, B and C are integers from 0-2, R 1 and R 2 are independently selected from the group consisting of methyl, ethyl, propyl and isopropyl, and X- is an anion that renders the final material soluble or suspendable in use; it is preferably an environmentally-acceptable anion; and further wherein A, B, C and are such that the final polymeric material has an average molecular weight of from about 5,000 to about 250,000.

The polyamine materials useful in the compositions and methods of the present invention are well known in the art. An example of such a polymer is a material sold under the trade designation Mazon TM 150 by

TM

Mazer T M Chemicals, Inc., a division of PPG.

The method for preparing such material is well known in the art.

In a preferred embodiment, the sum of A, B, and C is three More preferably, A, B, and C are each one (1) The average molecular weight of the polymeric materials for use in the preferred compositions and methods of the present invention is in the range of about 5,000 to about 150,000. Preferably, polymeric materials employed in the compositions and methods of the present invention are in the range of about 5,000 to about 50,000.

and still more preferably in the range of about 20,000 to about 30,000.

In general, the preferred polymeric materials of the present invention, and the methods derived therefrom, demonstrate a viscosity index range of about to 750 cps. In a more preferred embodiment, such polymer or polymeric materials employed in the compositions and methods of this invention demonstrate a viscosity of about to 500 cps, and still more preferably about 100 to about 500 cps In a highly preferred embodiment, the polymer materials used in the compositions of the present invention, and the methods derived therefrom, demonstrate viscosity of about 150 to about 400 cps.

WO 90/00906 PCT/US89/03041 The amount of polymer material that is employed in the actual use compositions treatment solution or medium) ard methods of the present invention will be an effective amount, an amount that will be sufficient to control the release or emission of unpleasant odors from the toilet holding tank or the toilet system for the desired length of time. In general, the preferred use compositions and methods of the present invention employ the polymeric materials described above in a toilet system, especially the holding tank, at a level of about .005 percent to about 1 percent, by weight, usually by weight of the treatment solution. More preferably, the compositions and methods of the present invention employ the polymer material at a level of about 0.01 to about 1, still more preferably in the range of about of 0.01 to about 0.5 and still more preferably about 0.02 to about 0.3 percent, by weight.

In one highly preferred embodiment, the polymeric material is employed at a level of about 0.02 to about 0.2 percent by weight.

It will be appreciated that the ranges described above for the level of a polymer material are mostly applicable to the final use solution, i. the final toilet holding tank treatment solution or medium generally a water solution after addition of the polymer.

It will be appreciated, however, that the level at which the polymer material is employed will depend upon whether the artisan is formulating a final use solution as described above, or an additive or concentrate solution to be used in turn to prepare or replenish a final use solution. In general, a much higher level of a polymer material will be employed in an additive composition because of its ultimate dilution via addition to the toilet system. The amounts and levels of components selected to prepare a concentrate or additive composition will generally be selected so that, when added to the O 90/00906 PCT/US89/03041 11 desired final use solution, the resulting use solution will contain an effective amount (include the preferred amounts) of the polymer material. In general, concentrate or additive compositions will comprise a concentrate of the selected polymer material in other agents which can be added to a toilet system to which have deodorization. For example, when employed as an additive or replenishing composition these values will be correspondingly higher as the additive or replenishing composition will be diluted when added to the holding tank to achieve these preferred ranges. Accordingly, a preferred additive composition would employ about 5 percent to about 50 percent of the polymeric material by weight of the additive composition.

For example and without limitation, a four oz. unit dosage formation would preferably employ about 5 percent to about 40 percent of the polymeric material, by weight of the additive composition; an eight oz. unit dosage formulation would preferably employ about 5 percent to about 20 percent of the polymeric material by weight of the additive composition; and a sixteen (16) oz. unit dosage formulation would preferably employ about 2 percent to about 10 percent of thG polymeric material by weight of the additive composition, and so on.

Optionally, other conventional or art-recognized additives may be employed in the compositions and methods of the present invention including the concentrate or additive compositions.

Preferably, such additives are also environmentally-acceptable and/or non-corrosive. Such materials include surfactants. Surfactants useful in the preferred compositions and methods of the present invention, including the concentrate or additive compositions of the present invention, include those selected from the group consisting of Tergitol 15S12 (Union Carbide) Polytergent SL-62 (Olin) Neodol 91-8 (Shell); and Igepal CO-730 or CA-730 (GAF) WO 90/00906 PCT/US89/03041 12 Another class of additives useful in the compositions and methods of the present invention, including the preparation of a concentrate or additive composition, are fragrances. Suitable fragrances include Orchidia Floral Fragrance 409006, Givaudan Perfume Oil PNAB 7989; Intarome Bouquet 26269; and Naarden N13736.

Another class of additives that may be employed in the compositions and methods of the present invention, including the preparation of an additive or concentrate composition, are other deodorizers. These deodorizers may include those of the conventional anti-microbial-anti-bacterial type or the masking type.

Such materials include formaldehyde and formaldehyde derivatives, buffers, quaternary ammonium materials, and the like. However, in a preferred embodiment, the methods and composition are substantially free of formaldehyde or formaldehyde derivatives.

Another class of additives useful in the compositions and methods of the present invention, including the preparation of a concentrate or additive composition, are dyes or pigments. Such materials are generally added to esthetically mask the appearance of any visible portion of the holding tank solution. Such materials include Basic Blue 26, Basonyl Blue 640; Basic Yellow 65; Flexo Yellow NB-117; Basic Green 4; and Basonyl Green NB 832; all manufactured by BASF.

Another class of agents that can be employed in the compositions and methods of the present invention, including the formulation of a concentrate or additive solution or composition, are thickeners. These are preferably selected from the group consisting of UCARE polymer JR-cationic cellulose ether (Amerchol); Bermocoll nonionic cellulose ether (Berol Chemical; and Polyox-ethylene oxide (Union Carbide) and Cellosize-hydroxy ethyl cellulose (Union Carbide).

It will be appreciated from above that the methods of the present invention involve controlling or 4INVO 90/00906 PCT/US89/03041 13 eliminating odor from a toilet system that includes a toilet tank by adding to a toilet tank in need of said odor control an effective amount of a polymeric material described above.

The following examples of the compositions and methods of the present purpose are for illustrative purposes only, and are not intended to be limiting.

004% 0.15% .002% .002% EXAMPLE I IN USE Mazon 150 Polyamine Naarden N13736 Igepal CO-730 Basic Blue 26 Bermocoll Water .005 .0008 .002 0 0 qs 8% 1% 1% EXAMPLE II CONCENTRATE Mazon 150 Polyamine Naarden N13736 Igepal CO-730 Basic Blue 26 Bermocoll Water 0.5 1 0 0 qs

I

7 A.

Claims (23)

1. A method of controlling the odor from a toilet system including a holding tank comprising employing in said toilet system an aqueous solution containing an effective amount of a polymeric material comprising a polyamine having the following formula 2 R n wherein A, B and C are integers from 0-2, R, and R2 are independently selected from the group consisting of methyl, ethyl, propyl and isopropyl, and X- is an anion; and further wherein A, B, C and n are such that the final polymeric material has an average molecular weight of from 5,000 to 250,000. .0

2.anA method according to claim 1 wherein the sum of A, an C is 3.

3. A method according to claim 1 wherein A, B and C are 1, and n is such that said final polymeric material has 0 .0 an average molecular weight of 5,000 to 250,000.

4. A method according to any one of claims 1 to 3 wherein the polymer material has an average molecular weight of 5,000 to 150,000. A method according to any one of claims 1 to 3 wherein the polymer material has an average molecular .TiAA. weight of 20,000 to 30,000. 920217,EEDAT.0 14,a:\40440the.res, 14 -i ;i la~-~o 15

6. A method according to any one of claims 1 to wherein the polymer material demonstrates a viscosity of to 750 cps.

7. A method according to any one of claims 1 to wherein the polymer material demonstrates a viscosity of to 500 cps.

8. A method according to any one of claims 1 to wherein the polymer material demonstrates a viscosity of 150 to 400 cps prior to addition.

9. A method according to any one of claims 1 to 8 wherein the polymeric material is employed at a level of 0.005 to 1 percent by weight of the treatment solution or medium. A method according to any one of claims 1 to 8 •O wherein the polymeric material is employed in the toilet \system at a level of 0.01 to 1 percent by weight.

11. A method according to any one of claims 1 to 8 wherein the polymeric material is employed in the toilet o* *system at a level of 0.02 to 0.3 percent by weight of the final toilet tank water solution.

12. A method according to claim 4 wherein the polymeric material is employed in the solution at a level of 0.02 to 0.2 percent by weight.

13. A method according to any one of claims 1 to 12 that additionally comprises employing a surfactant.

14. A method according to any one of claims 1 to 13 that additionally comprises employing a fragrance. A method according to any one of claims 1 to 14 that 920217,EEDAT.014,a:\40440the.res,15 -16- additionally comprises employing a deodorizer.

16. A method according to any one of claims 1 to 15 that additionally comprises employing a dye.

17. A method according to any one of claims 1 to 16 that additionally comprises employing a thickener.

18. A method according to any one of claims 1 to 17 wherein the anion is environmentally-acceptable.

19. A method according to any one of claims 1 to 17 wherein the anion is chlorine. A method according to any one of claims 1 to 19 wherein the aqueous solution is substantially free of formaldehyde or formaldehyde derivatives.

21. A toilet system additive composition comprising an effective amount of a polymeric material having the formula *0 2-j *9 R 1 n wherein A, B and C are integers from 0-2, R 1 and R 2 are independently selected from the group consisting of methyl, ethyl, propyl and isopropyl, and X- is an anion; and further wherein A, B, C and n are such that the final polymeric material has an average molecular weight of from 5,000 to 250,000 and a surfactant. 920217,EEDAT.014,a:\40440te.res, 16 ~L _i 17-

22. A composition according to claim 21 which additionally comprises a fragrance.

23. A composition according to claim 21 or claim 22 which additionally comprises a dye.

24. A composition according to any one of claims 21 to 23 which additionally comprises a thickener. A composition according to any one of claims 21 to 24 wherein the final additive composition employs the polymeric material is present at a level of 5 percent to percent, by weight of the composition.

26. A composition according to any one of claims 21 to which is substantially free of formaldehyde or formaldehyde derivatives.

27. A method according to claim 1 substantially as hereinbefore described with reference to the examples.

28. A composition according to claim 21 substantially as hereinbefore described with reference to the examples. SDATED this 17th day of February, 1992. 9 THETFORD CORPORATION •By Its Patent Attorneys DAVIES COLLISON CAVE 920217,EEDAT.0 14,a:\40440the.res, 17 I I I I I ii U.1 -I INTERNATIONAL SEARCH REPORT Informational A oolcatiort No =C T/!JS8~9/03041 I. CLA33SICATION Or SU13JECT MATTER itrerat classificjlion symbols aociy. inldicate all) Acccrd,ngm (o 1,ternalionat Patent Classification or to both Nat-onat Classification and IPC IMC( 4 ,6i1L 2/00; US 4 2 2 /2 8 Wt FIELDS SEARCHED Minimum Documentation Searched Classufcuiron System I Classification Symbol$ US: 422/5,6, 28, 29,33. Documentation Searched other tharn Minimum Documentation to the Ettent that such Documents ire Included in the Fields Searched 6 Ill. DOCUMENTS CONSIDERED TO 8E RELEVANT 14 Category Citation of Document. t G with indication chert appropriate, ot the retevant passage* i1 Retlent to Claim No. Ifa Y US,1 A, 4,539,179 (Xeloy) 03 September 1935, 1-26 see the enk1re document. Y US, A, 4,536,367 (Hung et al.) 20 AugZust 1-26 1985, see the entire document. Y US, A, 4,446,0 (Nudel et al.) 01 M~ay 1984 1-26 see the entire document. *SPIRCIat categories ot cited documents: i0 "T titer document oubtlshed after the international fiting date ocuent ernng he gnerl sate f te at h- -1not or priority data and not In conflict with the aptlication but c ocnde nn t e eertiuarsteeatte F tc tf~ itead to understand the principle or theory uinderlying the consdere tobe a daticuar eticnceinvention earlier document but pubtished on or atter the Interniational document al Particular relevance; the claimed invention riling date cannot be considered novel or csnnol be considered to "L document which may throw doubts on priority cia-mlat or involve an inventive step w hich i t cited to establish the publication date at another document of particular relience: the claims, Invention, citatton or other speciat reason (as soocified!) cannot be considered to involvo en inventive asoe wheny IttO document referring to an oral disclosure, use, eahibitien or document Ie combined with one or more other such docu- Other meane ments. such combination being obvious to a person silled P" document oubti Ihhd prior to the internetional filing date but in thet art. later then the priority date claimed document member of the same patent temily IV. CERTtFICATION Date ot the Actual Completion ot the Internationat Search I Oat* of Maling of this International Search Report1 12 October 1989 26O198 International Searching Authority I Signature ot Authorited Officer Is U. "ALLEN F,,io PCt/ISA/21 0 (seco~nd &heot) (J'Ay 1988)