AU604854B2

AU604854B2 - Machine dishwashing process

Info

Publication number: AU604854B2
Application number: AU12576/88A
Authority: AU
Inventors: Jochen Blecher; Berthold Lagenstein
Original assignee: DIVERSEY CORP
Current assignee: Diversey Inc
Priority date: 1987-03-03
Filing date: 1988-03-02
Publication date: 1991-01-03
Anticipated expiration: 2008-03-02
Also published as: AU1257688A; ES2026250T3; DK114888D0; EP0282214B1; ES2026250T5; DE3707366A1; DK171583B1; DE3865324D1; CA1324945C; DK171583B2; EP0282214B2; DK114888A; EP0282214A1

Description

AUSTRALIA

Patents Act COMPLETE SPECIFICATION

(ORIGINAL)

Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority Related Art: 0000 0 0 0 0o0C 0 0 00 0 0 00 a 00 0 0 0 0 0 0 It 0 a E 0 01C a or 0 a10 06 a 0 a 0 0 APPLICANT'S REF.: JHW/vm 2859 Name(s) of Applicant(s): DIVERSEY CORPORATION Address(es) of Applicant(s): 201 City Centre Drive, Mississauga, Ontario L513 2Z9, Canada Actual Inventor(s): Jochen Blecher Berthold langenstein Address for Service is: PHILLIPS, ORMONDE AND FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street Melbourne, Australia, 3000 Complete Specification for the invention entitled: MACHINE DISHWASHINC PROCESS The followir.', statement is a full description of this invention, including the best method of performing it known to applicant(s): DIVERSEY CORPORATION P19/3/84 ~iY PLli-- Machine Dishwashing Process FIELD OF THE INVENTION This invention relates to a machine dishwashing process; more particularly, it relates to an improvement in continuous or non-continuous machine dishwashing, whether conducted using a single tank, multitank or conveyor type machine.

BACKGROUND OF THE INVENTION In a typical machine dishwashing process, tableware or cookware, such as dishes soiled with food 0 00 o0 0 0000 00 0 0 0 000 0 00 0 0 0 000 0 00 0 S0ooo0 0 00 0 o o0 0 00 0 0 0 0 00 0 00 00 0 0 oo 00 00 0 0 0 0 0 00 0 0 0 0 0 0 0 0 o00 remains, trays, cutlery and lipstick-smeared glasses, is intensively sprayed with water in a prewash zone or prew.ash cycle. The water used for the prewash may be cold or preheated fresh water or cooling water from a 15 vapor condensation process, but is generally overflow water of a wash liquor, which is generally sprayed onto the articles under relatively low pressure and in relatively large amounts using suitably located spray nozzles.---After-this prewash zone or prewash cycle, the articles enter the actual wash zone or wash cycle, where they are again vigorously sprayed this time with a wash liquor.

The wash liquor is generally water at a temperature of from 50 to 60°C to which a liquid or 25-- powder-form detergent is added. In order to remove grease, starch, stains and protein with sufficient reliability, for example powder detergent or liquid detergent is added to water to provide from 0.1 to 0.3 weight percent of active cleaning agent in solution.

30 This resulting wash liquor is sprayed onto the articles by pump means through lower and upper nozzles and, in some cases, through additional lateral nozzles. The soil present on the articles is removed or at least swollen or softened and partially dissolved by the wash liquor. In following rinse zones or cycles, the swollen or softened food remains are removed and, at the same time, the wash liquor is rinsed off by water. In a final rinse zone or final rinse cycle, any residues of the wash liquor are removed by water at a temperature j L up to about 85"C. The final-rinse water consists of fresh water with an added rinse aid, which ensures that only an ultrathin film of water remains on the articles, which can evaporate in a following drying zone.

Even the use of relatively large amounts of detergent in regular conventional cleaning will not always avoid the need for periodic heavy-duty cleaning.

The object of this extra cleaning is to remove coatings of, for example water-insoluble stains or starch which have gradually built up, but which are not immediately discernible. For this heavy-duty cleaning, the articles are treated occasionally with a wash liquor containing several times the normal quantity of detergent.

Optionally, a manual pre-soak may be employed to the 15 same end. Both of these methods also mean additional pollution of the wastewater.

SUMMARY OF THE INVENTION 0 0o 00 0 0000 0o 0 0 000 0 00 0 0 0 000 0 00 0 0o o0 According to the present invention a surprisingly oo advantageous dishwashing is provided. The improved efficiency of cleaning obtainable may reduce labor, water and chemical consumption, hence lower pollution and rejects, while ensuring satisfactory cleaning even 0 00 00 o in adverse conditions.

o00 T T prZ nt invention providec a mac.Re 00 0 0 00 dishwashing process characterized in that a highly o o00 *o concentrated aqueous cleaning formulation is sp yed onto at least partially soiled articles and after a contact time, the cleaning formulation soil are cc 0 o000 removed in one or more subsequent st es.

o 0 30 The present invention also ovides a dishwashing machine adapted to effect su a process, for example by addition of extra spray ozles and associated systems and/or by modificatio to the control systems of the machine.

35 The aque s cleaning formulation may be derived ?ALI from powd -form or liquid materials. Generally, the W spray ecleaning formulation comprises at least we ht percent of one or more active cleaning agents.

0 a.l30 weight percent might be regarded as an -1 <4 -i The present invention provides a machine dishwashing process which comprises: applying at a low volume, and low intensity, a highly concentrated, aqueous detergent formulation onto at least partially soiled articles, the formulation being in substantially complete contact and substantially even distribution on the soiled articles; allowing the formulation an uninterrupted contact time with the articles of 2 to 100 seconds after application, during which time no additional cleaning formula or rinsing is applied; and subsequently removing the detergent formulation and soil from the articles.

C The present invention further provides a machine dishwashing process which comprises applying in fine mist

C

form without mechanical application a highly concentrated, atrc aqueous cleaning formulation onto at least partially soiled articles, the mist-like application of the cleaning formulation being in substantially complete contact and 20 substantially even distribution on the soiled articles, o006 oic allowing the fine mist of the cleaning formulation to o :contact the articles for a contact time of 2 to 100 CCtCseconds and subsequently removing the cleaning formulationii e and soil from the articles.

The dishwashing process of the present invention may be effected by an adapted dishwashing machine, for example by addition of extra spray nozzles and associated systems and/or by modifications to the control systems of the machine.

The aqueous cleaning formulation may be derived from powder-form or liquid materials. Generally, the sprayed cleaning formulation comprises at least 0.5 weight percent of one or more active cleaning agents. While, say, weight percent might be regarded as an -2a- 3 upper limit, the critical factor is that the formulation must remain sprayable. Preferably, the sprayed cleaning formulation comprises from 0.8 to weight percent, more preferably from 0.9 to 3 weight percent, of one or more active cleaning agents.

Generally, a contact time of at least two seconds will be sufficient for the desired chemical, as opposed to mechanical, action. In preferred embodiments, this may be from 5 to 100 seconds, in particular from 8 to seconds. So as to provide the desired prolonged intimate contact or "saturation", the "mechanical effect" of spraying is at least minimized, if not avoided. During this contact time, the articles being 00 washed are not deliberately sprayed.

o oo 0 15 In order to optimize results, it is important that o ooo 00 substantially the whole surface of a soiled article °000 should be contacted by the sprayed cleaning formulation 00oo o.

0 o and the amount of formulation sprayed and the manner in oooo which it is sprayed may be adapted bearing this aim in 0 0 mind. A fine, gentle mist-like spray is particularly desirable. In a conveyor-type machine, the belt speed will also be a factor. More particularly, the volume o0 0oo sprayed and/or the number and/or arrangement of spray S00 nozzles is/are selected so that low volume spraying will S0 25 ensure the desired type of complete coverage and even 00.000 0 0 distribution. The nature, volume and concentration of 0 0 the sprayed formulation may be varied, as may the spray means, depending, for example, on the load and, where oo00 0 0 appropriate, the motion and/or speed of the conveyor.

i oor 0 00 30 The present low volume/low intensity mist-like application of concentrated cleaning formulation is in contrast to the vigorous high volume spraying used in conventional dishwashing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Generally, a machine dishwashing process may comprise one or more prewash cycles or zones, which may be optional, for example to remove heavy soil, -one or more wash zones and one or more rinse zones. In 1 I o0 oo 00 0 0000 00 0 0 0 000 0 00 0 0 0 00 0 oo o oo 00 o oo o -0 0 0 0.0 0.

0 0 0 00 0 0 0 0 00 0 00 0 0 o oo oo oo 00 00 0 0 00 a 0 0 a a 0a 0 a a 0 *a accordance with the present invention, the unusually high concentration cleaning solution is sprayed somewhere prior to the final rinse, commonly as at least part of a wash cycle or in a wash zone.

While all of the cleaning agents required may be included in the sprayed concentrate, it may be advantageous to introduce additional cleaning formulation in a conventional manner at some stage of the process. This further material is generally not the same as the sprayed concentrate, but may merely be the same composition further diluted. The use of a complementary formulation particularly commends itself.

The balance of the complementary products may also be adjusted. For example, a high alkalinity spray might be 15 balanced by a lower alkalinity wash to follow. The present system also enables chemicals which would normally be incompatible when mixed in a single product to be used in conjunction, for example oxidizing agents, such as hypochlorite,-may-be used in the spray with, for example, water conditioning agents, such as NTA (nitrilotriacetate) being introduced later.

While the concentrated cleaning formulation is generally sprayed more or less throughout the appropriate part of the dishwashing process, it may be 25 used intermittently or occasionally, for example during the wash cycle in a non-conveyor type machine.

The aqueous cleaning formulation sprayed must be flowable, but may be in the form of a solution, emulsion or slurry, for example. Various materials are 30 known which will cause or facilitate at least some penetration and/or swelling and/or loosening and/or dissolution of soil. Typically, a basic cleaning formulation will comprise a source of alkalinity and a source of sequestering activity. Such formulations may be adapted to combat particular problems. For example, tea-stain removal might suggest the inclusion of bleaching agents, while products based on amylase may be useful for starch removal without alkalinity.

j For purposes of illustration, a machine for carrying out the present process may be a conveyor transport machine and may comprise a prewash zone, a wash zone, a rinse zone, a final rinse zone and a drying zone. Fresh water is only supplied to the final-rinse zone, subsequently passing cascade-fashion towards the prewash zone in countercurrent to the direction of transport of the dishes.

A simple product fairly efficient in removing built-up starch residues and stains may be formulated from the following Potassium hydroxide 20 30 wt Chelating agent(s) 15 25 wt SThreshold agent(s) 2 4 wt Dispersing polymer(s) 2 4 wt Wetting agent(s) 1 2 wt Balance water Optimization of such a product is possible and desirable. Such a product may be blended with water inline before being sprayed at a dilution of about 2.5 through suitable spray nozzles situated within the wash zone immediately before or after the conventional wash zone. Sprayed ware may then pass through part of the wash zone with the pumps turned off (unless there is already sufficient separation between zones) so as to allow a contact time of about 15 seconds, before reaching a further wash or rinse zone. Further detergent may be added by conventional means at other I stages to provide additional destaining and prevention 30 of incrustation of machine parts. Thereafter, the ware passes to a final rinse stage where rinse aid may be introduced.

After soiled dishes have been loaded onto the conveyor belt, in the prewash zone it is deluged in overflow water from the wash zone, which has a temperature of about 40°C. All coarse or relatively large quantities of food remains are thus removed from the dishes. The dishes then enter the actual wash zone.

In the wash zone, the dishes are sprayed with the highly concentrated detergent solution, each nozzle may be delivering in a fine spray or mist form as little as 6 1/hour and typically there will be from 3 to 10 nozzles.

The system is arranged or adapted to ensure that nothing disturbs the desired prolonged intimate contact.

The speed of the conveyor belt is advantageously selected so that the contact time of the detergent solution, depending on its concentration, is from 5 to 100 seconds, generally about 10 seconds. Such a contact time and the higJh concentration of the detergent solution ensure that all food remains on the dishes, especially grease (fats), starch, stains and protein, 0 O6 are completely removed and bacteria destroyed.

0000 oD 15 After this contact time, the detached food Sooo o oo remains, together ith the detergent solution sprayed oo co a on, are washed off by the subsequent stages using oo o o 00o conventional spray nozzles, the wash liquor consisting o -o of overflow water from the rinse zone and of rinsed-off, concentrated detergent solution and any additional dosed complementary cleaning formulation. With the process according to the present invention, there is no longer 0 00o 0o oo any need for the intermittent heavy-duty cleaning or the 0 00 oo manual pre-soak hitherto necessary.

0 0 a In the subsequent rinse zone, any loosened food and o soil remains still present on the dishes and residues of the wash liquor are rinsed off with clear water at a temperature of about 70oC. In the final- rinse zone, fresh water at a temperature of about 85°C with rinse o 30 aid added ensures that only a thin film of water remains on the dishes, which dries rapidly in the following drying zone either through the heat of the dishes or by introduction of hot air.

By virtue of the present process, dishes are reliably maintained to a consistent high standard of cleanliness.

Although preferred embodiments of the invention have been described herein in detail, it will be understood by those skilled in the art that variations 11 7 may be made thereto without departing from the spirit of the invention or the scope of the appended claims.

0 0 a 00 00 t 00 x0 C -4

I).

Claims

1. A machine dishwashing process which comprises: applying at a low volume, and low intensity, a highly concentrated, aqueous detergent formulation onto at least partially soiled articles, the formulation being in substantially complete contact and substantially even distribution on the soiled articles; allowing the formulation an uninterrupted contact time with the articles of 2 to 100 seconds after application, during which time no additional cleaning 00formula or rinsing is applied; and o o o000oo subsequently removing the detergent formulation and 00 o o soil from the articles. o oo00 2. A process as claimed in claim i, wherein the contact 000 0 0,ao 0 time ranges from 5 seconds to 100 seconds. So 3. A process as claimed in claim i, wherein the contact ooo 0 time ranges from 8 seconds to 25 seconds.

4. A process as claimed in any one of claims 1 to 3, wherein the detergent formulation comprises from at least 0 0 20 0.5 weight percent to about 30 weight percent of at least oooo one active cleaning agent. 0000 o o o o 00 5. A process as claimed in claim 4, wherein the active 0...cleaning agent comprises an alkali hydroxide.

6. A process as claimed in any one of claims 1 to which further comprises: prewashing a soiled article; 00 washing a soiled article; rinsing a soiled article; and 0 000 wherein the concentrated cleaning formulation is applied o0 o 0 prior to any final rinse.

7. A process as claimed in claim 6, wherein the cleaning formulation is applied during the washing of a soiled article.

8. A process as claimed in any one of claims 1 to 7, wherein the dishwashing process is conducted in a conveyor-type dishwashing machine, the process further comprising: adjusting the movement of the conveyor to ensure thorough contact and even distribution of the detergent formulation on the soiled article. S9. A process as claimed in any one of claims 1 to 8, I i--i:l'ii_ i I- -1 which further comprises: adding a non-identical cleaning formulation during the dishwashing process, after the contact time with the application of the cleaning formulation. The process as claimed in any one of claims 1 to 9, wherein the applied detergent formulation comprises from at least .8 to 10 weight percent of at least one active cleaning agent.

11. A process as claimed in any one of claims 1 to wherein the alkali detergent formulation comprises between .9 and 3.0 weight percent of at least one active cleaning agent. c 12. A machine dishwashing process which comprises S applying in fine mist form without mechanical application a highly concentrated, aqueous cleaning formulation onto at least partially soiled articles, the mist-like application of the cleaning formulation being in substantially complete contact and substantially even distribution on the soiled articles, allowing the fine o0o 20 mist of the cleaning formulation to contact the articles 0000 o0o for an uninterrupted contact time of 2 to 100 seconds and 0000 00 0 subsequently removing the cleaning formulation and soil 0o0o from the articles.

13. A dishwasing machine characterised in that it is adapted to effect a process as claimed in any one of oe claims 1 to 12. t c DATED: 24 SEPTEMBER, 1990 PHILLIPS ORMONDE FITZPATRICK Attorneys For: DIVERSEY CORPORATION S2185Z y r\ -9- i