WO2005094660A1

WO2005094660A1 - Drying medium for drying and polishing cutlery, table ware, glass, porcelain goods and silver items

Info

Publication number: WO2005094660A1
Application number: PCT/EP2004/050257
Authority: WO
Inventors: Friedel Rings
Original assignee: Ecolab Inc.
Priority date: 2004-03-04
Filing date: 2004-03-04
Publication date: 2005-10-13

Abstract

The invention relates to a drying medium comprising 0,01-20 wt% of a antimicrobial agent which is used 9 for drying and polishing wet cutlery, wet table ware, wet glass and porcelain goods.

Description

Drying medium for drying and polishing cutlery, table ware, glass, porcelain goods and silver items

[0001] The invention relates to a drying medium for drying and polishing cutlery, tableware, glass and porcelain goods. In institutional kitchens like restau- rants, canteens, public service catering facilities and the like the cutlery and tableware like plates, saucers, glasses etc. are washed and dried in automatic dish washing machines. The drying is initiated by using a rinse aid, supported by a shower of hot air. The load with the cutlery and tableware is passed through a tunnel where jets of very hot air dry the load through evaporation.

[0002] However, after the drying process in the institutional dishwashing machines, the cleaned objects still show water spots, traces of limestone, rings and small marks, even in cases where softened water was used for the dishwashing process. The water and the residues have to be removed by manually rubbing the cutlery and tableware for example with alcohol or vinegar, especially in the case of silver metal to remove the tarnish.

[0003] To avoid this manual after-treatment vibratory dryers are used which dry and polish the articles coming out from the dishwasher. The hot and wet metal items are collected on exit from the dishwasher and are placed in the vibratory dryer where they remain for 15 to 100 seconds. The vibratory dryer contains a tank for receiving the wet articles with a loading shoot and an exit shoot. Furthermore it contains a drying material which is arranged in the tank and receives the wet articles. Furthermore the drying process is supported by a heater which is integrated in the vibratory dryer.

[0004] Such vibratory dryer is for example described in DE 100 65 841, EP 0 882424 A2 and EP 0 880 935 A1 . The tank includes a loading shoot and an exit shoot on the outer side of the tank. The drying medium is arranged in the tank and receives the wet articles. A vibrator is placed in the dryer for vibrating the tank to cause the wet articles to move relatively to the drying material. By such vibration the drying medium absorbs the moisture from the wet articles and additionally the drying material polishes the articles.

[0005] The drying material absorbs moisture from the surface of the wet articles and during the same time polishes the articles. This process lasts about 30 seconds to 2 minutes. When taken out, the cutlery and the tableware is perfectly dry without any trace of limestone or marks or water and detergent stains. The drying material which is used in such vibratory dryers normally is a granulate of a moisture-absorbent material. The most common material used is com cob granulate, also called maizorb granulate. Maizorb granulate is FDA-compliant and an excellent drying medium with the side effect that cutlery and tableware is also polished during drying. The maizorb granulate is used in the vibratory dryers up to four to six weeks before it is exchanged against new maizorb granulate. During the use of the maizorb granulate moisture is absorbed by the maizorb granulate and also food residues from the cutlery or the dishes enter the granulate.

[0006] As the normal process temperature in the vibratory dryer lies between 40° C and 60° C and as there is an organic support material present, this provokes an increase of microbial dirt and microorganisms in the maizorb granu- late. This is a fundamental risk as there is the danger that cutlery and tableware is polluted during the drying and polishing process in the vibratory dryer by microorganisms. The same risk occurs if as drying media other porous materials are used, for example porous polyamide granulates or other organic materials based on cellulose like walnut-shells.

[0007] At present it is state of the art to provide vibratory dryers with strong ultraviolet lamps so that during processing the drying medium is irradiated with ultraviolet light in order to decrease the concentration of microorganisms in the drying medium. However, the drying medium has a very large inner surface, that means it has pores and crevices in which the microorganisms can accumulate. In these areas the ultraviolet light has no effect as the ultraviolet irradiation only reaches the surfaces of the particles. A further disadvantage is that qualified UV- lamps are very expensive, anyway all UV-lamps show a significant loss of performance after some time.

[0008] Therefore it is the technical object of the invention to provide a new drying medium for drying and polishing wet glass, porcelain goods and cutlery which is substantially free of microorganisms and can be processed in a vibratory dryer over the desired period of time without an increase of microorganisms.

[0009] This technical problem is solved by a drying medium comprising 0.01 to 20 wt-%, preferably 0.05 to 5 wt-% and most preferred 0.1 - 1 wt-% of an antimicrobial agent.

[0010] Surprisingly it was found that if an antimicrobial agent is mixed to the drying medium, the occurrence of microorganisms is rapidly decreased and the period of use of the drying medium is extended to the desired period of four to six weeks without showing any microbial decomposition.

[0011] In a preferred embodiment the drying medium is a granulate with a particle size of from 0.5 to 2 mm, preferably 0.5 to 1 mm. The drying medium is moisture-absorbent in order to absorb the moisture on the surface of t »e tableware or the cutlery coming out from the dishwashing machine. Furthermore, the drying medium has preferably a Mohs hardness from 2 to 5, more preferred 2 to 4 and most preferred from 2.5 to 3.5. If the Mohs hardness is below 2, the drying medium is too soft so that the cutlery or the tableware is not polished. If the drying medium has a hardness over 5, it leads to scratches on the surface of the cutlery or tableware.

[0012] In a further preferred embodiment the drying medium comprises porous polymer particles or natural organic particles on cellulose basis. In a most preferred embodiment the drying medium is selected from the group consisting of porous polyamide particles, corn cob, also known as maizorb, or walnut-shells and mixtures thereof. These drying media allow a drying and polishing treatment of cutlery and tableware with care. Especially maizorb granulate and porous polyamide granulate have a very good moisture uptake availability. Furthermore, they show a very good polishing effect. The particle form of the granulate is not limited thus the granulate can be spherical, elliptical or cylindrical.

[0013] The antimicrobial agent is an active chlorine-containing compound and/or an active oxygen-containing compound. That means that during use of the compounds it develops chlorine or oxygen both having an antimicrobial effect. In a preferred embodiment the antimicrobial agent is selected from the group consisting of monochloroisocyanuric acid its salts, dichloroisocyanuric acid its salts, trichloroisocyanuric acid its salts calcium hypochlorite, kalium hypochlorite, sodium hypochlorite, peroxy acids and their salts, hydrogen peroxide, perborate salts and mixtures thereof.

[0014] The above-mentioned compounds develop chlorine or oxygen when mixed with moisture and heated. Chlorine and/or oxygen which develops in the drying media, is absorbed by the pores of the drying medium and continuously delivered to the drying medium. Furthermore, in the case of active chlorine- containing compounds it was found that only a very slight odor of chlorine gas occurred. Furthermore it was found that the more moisture is in the drying granulate the more chlorine is developed. This supports the antimicrobial effect of the drying medium because with increasing time of usage of the granulate there is a higher danger of pollution with microorganisms. It seems that there is a chemical balance between chlorine and hypochlorite which makes the drying medium comprising the antimicrobial agents highly effective.

[0015] In a preferred embodiment and in the case if cutlery of silver or sil ver tableware is processed in the vibratory dryers, it is preferred that the drying medium further comprises additives for polishing and cleaning tarnished silver. For this purpose solutions, soaps, powders and pastes can be used comprising borax, ammonia, sodium thiosulfate, diluted mineral acids, citric acid or thiourea. In a further preferred embodiment the drying medium can additionally contain usual abrasives for cleaning and polishing.

[0016] The drying medium according to the invention is used for drying and polishing wet cutlery, wet tableware, wet glass and porcelain goods. It shows a good drying and polishing effect. The hot and wet cutlery as well as tableware which remains for a very short time in the dryer, is perfectly dry without any trace of limestone or marks or detergent stains when taken out. Furthermore, the polishing effect of the drying medium according to the invention maintains the shine especially on metal tableware and cutlery inhibiting or delaying the visible effects of aging. Furthermore, by this method the manual re-polishing of the metal surfaces can be avoided and this means a . lower risk of microbiological contamination:

[0017] A further object of the invention is a method for drying and polishing wet cutlery, wet tableware, wet glass and porcelain goods comprising the steps of loading the wet cutlery, wet tableware, wet glass and porcelain goods into a tank of a vibratory dryer, filling the drying medium according to the invention in the tank, vibrating said tank with said drying medium and the cutlery and tableware whereby the drying medium absorbs the moisture from the wet cutlery, wet tableware, wet glass and porcelain goods and polishes it. In a preferred embodiment the tank is heated to a temperature from 30 to 70° C, preferably from 40 to 60° C.

[0018] The following examples show the invention in more detail without limiting it.

[0019] EXAMPLES

[0020] Example 1 Chlorine content of drying medium

[0021] First steps were made with contents of trichloroisocyanuric acid, coarse grain of 5 % and were found too intensive. At least amounts of 0.5 % 5 showed sufficient and long lasting effects. The loss of active chlorine was < 15 % after 4 weeks at ambient temperatures and 5% water added.

[0022] Trichloroisocyanuric acid in granulated form with a reduced amount of fine particles is added to corn cob in an amount of 3 wt-%. This mixture is filled in the vibration tank of a vibratory dryer. At the same time the drying medium is o heated up to a temperature between 40 and 60° C.

[0023] To simulate the advanced degeneration of the drying medium water in amount of 8 wt-% was added to the drying medium. After that the chlorine content of the drying medium was measured. 0.05 ppm chlorine was found. Only directly on the surface of the drying medium a slight chlorine odour was noticed.s However, no chlorine could be measured above the surface of the drying medium.

Claims

1. Drying medium comprising 0.01 - 20 wt-% of an antimicrobial agent.

2. Drying medium according to claim 1 , wherein the drying medium is a granulate with a particle size of from 0.5 to 2 mm.

3. Drying medium according to claim 1 or 2, wherein the drying medium is moisture absorbent and has a Mohs hardness from 2 to 5

4. Drying medium according to anyone of claims 1 to 3, wherein the drying medium comprises of porous polymer particles or natural organic particles on cellulose basis.

5. Drying medium according to anyone of claims 1 to 4, wherein the drying medium is selected from the group consisting of porous polyamide particles, com cob, walnut shells or mixtures thereof.

6. Drying medium according to anyone of claims 1 to 5, wherein the antimicrobial agent is an active chlorine containing compound and/or an active oxygen con- tainiπg compound.

7. Drying medium according to anyone of claims 1 to 6 wherein the antimicrobial agent is selected from the group consisting of monochloroisocyanuric acid and its salts, dichloroisocyanuric acid and its salts, trichloroisocyanuric acid and its salts, calciumhypochlorite, kaliumhypochlorite, sodiumhypochlorite, peroxy ac- ids and their salts, hydrogen peroxide, perborate salts and mixtures thereof.

8. Drying medium according to anyone of claims 1 to 7, wherein the drying medium further comprises additives for polishing and cleaning tarnished silver.

9. Drying medium according to anyone of claims 1 to 8 wherein the drying medium further comprises further abrasives for cleaning and polishing.

10. Method for drying and polishing wet cutlery, wet table ware, wet glass and porcelain goods comprising the steps of a. filling the drying medium according to claims 1 to 9 in the tank, and b. loading wet cutlery, wet table ware, wet glass and porcelain goods into a tank, c. vibrating said tank with the drying medium and the cutlery, table ware, wet glass and porcelain goods, whereby the drying medium absorbs the moisture from the wet cutlery, wet table ware, and polishes it.

11. Method according to claim 10 wherein the tank is heated to a temperature from 30 to 70 °C.

12. Use of the drying medium according to claims 1 to 9 for drying and polishing wet cutlery, wet table ware, wet glass and porcelain goods