EP3076849A1

EP3076849A1 - A washer comprising antimicrobial additive

Info

Publication number: EP3076849A1
Application number: EP14789567.6A
Authority: EP
Inventors: Merve ZAKUT; Osman Gokhan Ersoy
Original assignee: Arcelik AS
Current assignee: Arcelik AS
Priority date: 2013-12-04
Filing date: 2014-10-27
Publication date: 2016-10-12
Also published as: WO2015082134A1

Abstract

The present invention relates to a washer (1) having a sealing element (6) comprising antimicrobial material and thereby preventing formation of bacterial plaque and mold on its surface. By means of the present invention, the hygienic conditions inside the washing chamber (3) are improved.

Description

A WASHER COMPRISING ANTIMICROBIAL ADDITIVE

The present invention relates to a washer wherein the hygienic conditions inside the washing chamber are improved.
The washer of the present invention is a dishwasher or a washing machine. In the said washers, a sealing element, for example a gasket or bellows, is used between the door and the washing chamber in order to provide leak-proofing. The sealing element is generally produced from elastomeric materials like ethylene propylene diene monomer (EPDM) rubber. Bacterial plaque and mold formation is observed on the sealing element in the course of time as a result of repeated washing operations. The said bacterial plaque or mold creates problems in terms of the washing process hygiene. Bacterial plaque and mold formation increases particularly in between the folds of the sealing element or at points that are hard to reach by the washing water.
In the state of the art International Patent Application No. WO2009083398, a washer is disclosed having a sealing element that comprises antimicrobial material thereby preventing the formation of bacterial plaque and mold on the surface thereof.
The aim of the present invention is the realization of a washer wherein formation of bacterial plaque and mold on the sealing element disposed between the door and the washing chamber is prevented.
In the washer realized in order to attain the aim of the present invention, explicated in the first claim and the respective claims thereof, the sealing element disposed between the washing chamber and the door comprises an antimicrobial additive which is tea tree oil. The tea tree oil, that is also called “oil of melaleuca, Terpinen-4-ol type”, is defined in the standard of ISO 4730 (2004). The sealing element is produced from a material that is the mixture of EPDM and tea tree oil.
In an embodiment of the present invention, the sealing element is obtained by mixing 99 – 97% EPDM by weight and 1 – 3 % antimicrobial additive material by weight.
In an embodiment of the present invention, the washer is a dishwasher or a washing machine.
By means of the antimicrobial additive material added into the material from which the sealing element is produced, the formation of bacterial plaque and mold on and in the vicinity of the sealing element is prevented.
The washer realized in order to attain the aim of the present invention is illustrated in the attached figures, where:
Figure 1 – is the perspective view of a washer when the door is in the closed position.
Figure 2 – is the perspective view of a washer when the door is in the open position.
Figure 3 – is the detailed perspective view of the door of a washer and the sealing element thereon.
Figure 4 – is the view of detail A in Figure 3.
The elements illustrated in the figures are numbered as follows:
1 – Washer
2 – Body
3 – Washing chamber
4 - Loading port
5 – Door
6 – Sealing element
The washer (1) comprises a body (2), a washing chamber (3) wherein the washing process is performed, a loading port (4) through which the items to be washed are loaded into the washing chamber (3), a door (5) that covers the loading port (4) and a sealing element (6) disposed between the loading port (4) and the door (5).
Formation of bacterial plaque and mold on the sealing element (6) is prevented by adding antimicrobial additive substance into the material from which the sealing element (6) is produced. The sealing element (6) is produced from thermoplastic elastomer (TPE) material. Tea tree oil (TTO) is used as the antimicrobial substance. The tea tree oil, that is also called “oil of melaleuca, Terpinen-4-ol type”, is defined in the standard of ISO 4730 (2004).
The sealing element (6) is subjected to high temperatures (40^oC – 70^oC) during the washing process and is continuously in contact with the washing water containing cleaning substances dissolved therein and in an environment where the rate of humidity is high. In order for the sealing element (6) to continue the desired antimicrobial effect during the usage life of the washer (1), the ratio of the tea tree oil (TTO) in the sealing element (6) is determined by taking into consideration the environmental conditions formed in the sealing element (6) region during the washing process.
Samples are created by using antimicrobial material in the ratio of 1 % and 3 % by weight for determining the amount of antimicrobial material to be added into the sealing element (6) and the ratio of the tea tree oil that provides continuity of the antimicrobial effect in the sealing element (6) is determined by subjecting the samples to various tests.
Tests
In the method of the present invention, the anti-bacterial effectiveness of the materials developed against E. coli (ATCC 25922) and S. aureus (ATCC 6538) microorganisms is determined in accordance with the standards of “JIS Z 2801 – Antimicrobial products – Test for antimicrobial activity and efficacy”. In these tests, for each sample, six materials containing additive and six additive-free reference materials are used. In these tests, two different material conditions (concentration or additive ratio) can be tested in parallel together with the reference material and it takes approximately one week together with evaluation of the test results. At the end of these tests, the effectiveness of the materials against E. coli and S. aureus bacteria can be expressed as percentage reduction and/or the logarithmic reduction. Log 2 reduction corresponds to 99 %, log 3 reduction to 99.9 % and log 4 reduction to 99.99 % sufficient effectiveness.
In the test method of the present invention, the standard “ISO 846 Plastics -- Evaluation of the action of microorganisms” is planned to be used in order to determine the anti-fungal effectiveness of the developed materials against mold type microorganisms. In the tests that are conducted with 5 different types of mold which are defined in the standard, for each condition ten materials containing additive and five additive-free reference materials will be used. The different characteristics of the material developed can be evaluated in accordance with three different methods defined in the standard.

Method A: According to the test method defined as “Method A”, the feature of the material forming food source for fungal/mold growth can be examined,
Method B: the feature of the material inhibiting fungal/mold growth can be examined and
Method B’: the feature of suppressing fungal/mold growth in an environment where growth has taken place can be examined.

For each of the above defined methods, mold growth on plates at the end of an incubation period of 4 weeks can be evaluated visually. At the end of the visual evaluations, the anti-fungal effectiveness of the material can be defined as present / absent and/or defined comparatively to the other conditions that are tested.
In the operational tests, items with standard dirt are loaded into the washer (1) and the standard washing program of the washer (1) is operated. 40^oC is used as the washing temperature. This process is repeated for 600 cycles. The antimicrobial effectiveness of the sealing element (6) is measured before the first cycle and after the cycles of 100, 300, 450 and 600 with the JIS Z 2801 method. For every condition, tests are carried out with three washers (1) and the average results are given in the following tables.
Results of the tests are given below:
In this sample, the sealing element (6) comprises antimicrobial additive material of 1 %, 3 % by weight and TPE material with the ratio of 99 % and 97 %. The test results are given in Table A and the performance results in Table B.
Table A

Table 1

Washing Temperature (°C)	Cycle Duration (hours)	Number of Cycles	Test	1% TTO	3% TTO	Comments
-	-	-	JIS Z 2801: 2000E	Log 5.1	Log 6.2	Effectiveness sufficient
			ISO 846	1	1	Colony is not observed on the surface .
40	2	100	JIS Z 2801: 2000E	Log 4.8	Log 5.5	Effectiveness sufficient
40	2	300	JIS Z 2801: 2000E	Log 4.1	Log 5.5	Effectiveness sufficient
40	2	450	JIS Z 2801: 2000E	Log 3.7	Log 4.3	Effectiveness sufficient
40	2	600	JIS Z 2801: 2000E	Log 3.7	Log 4.1	Effectiveness sufficient

Table B

Table 2

TEST METHOD	y% EPDM	97% EPDM	99% EPDM
TEST METHOD	x% Silver	3% TTO	1% TTO
SPECIFIC GRAVITY , g/cm3	1.11	1.12	1.11
HARDNESS , Sh A -ISO 7619-1	41.00	41.00	41.00
TENSILE STRENGTH ,N/mm2 - ISO 37	8.87	8.10	8.80
ELONGATION AT BREAK , % - ISO 37	555.00	525.50	553.00
TEAR STRENGTH -ISO 34-1B	24.60	24.50	24.50
ABRASION A mm3 - ISO 4649-A	304.40	292.80	300.30
DEFORMATION UNDER PRESSURE.,% (3 days 100°) - ISO 815-1	55.80	51.70	55.80

The tests that are done show that this sample is successful in preventing growth of bacteria and mold.
The tests that are done show that this sample is successful in preventing growth of bacteria and mold. The sealing element (6) comprises EPDM material of 99 – 97 % by weight and antimicrobial additive material with the ratio of 1 – 3 %.
In the washer (1) of the present invention, the antimicrobial material in the sealing element (6) makes the bacteria and mold on the surface of the sealing element (6) ineffective during the washing process. The antimicrobial material depolarizes the electro-potential of the cell membrane and prevents the bacterial / fungal transfer process. Consequently, the formation of bacterial plaque and mold on the surface of the sealing element (6) is prevented.
The tea tree oil (TTO) mixture used in the sealing element (6) provides important advantages with respect to the EPDN – silver mixture. The EPDM material used in the sealing elements (6) is a thermoset material produced by vulcanizing with sulphur. Since sulphur reacts with silver based antimicrobial additive material, the use of silver based materials cannot provide the desired antimicrobial effect on the sealing element (6). Therefore, in order to use silver-based antimicrobial materials as additive, vulcanization with peroxide must be performed. Vulcanization with peroxide causes the problem of bad odor. Since the formation of these odors in the dishwasher or the washing machine is not desired by the user, vulcanization with peroxide is avoided.
In an embodiment of the present invention, the sealing element (6) comprises EPDM material of 97 – 97 % by weight and antimicrobial additive material with the ratio of 1 – 3 %.
In an embodiment of the present invention, the sealing element (6) is produced from thermoplastic elastomer (TPE) which is polystyrene / elastomer block copolymer material. TPE presents advantages in terms of recyclability and ease of production. The TPE material is polystyrene / elastomer copolymer (for ex. SEBS or SBS) or thermoplastic vulcanizate (EPDM/PP). The TPE material used in the sealing element (6) is preferably a thermoplastic vulcanizate obtained from the mixture of EPDM and polypropylene (PP) and is in granule form.
In an embodiment of the present invention, the sealing element (6) is produced from thermoplastic elastomer (TPE) which is a thermoplastic vulcanizate (TPV) derived from EPDM and polypropylene (PP).
In an embodiment of the present invention, the washer (1) is a dishwasher and the sealing element (6) is the gasket between the loading port (4) and the door (5).
In another embodiment of the present invention, the washer (1) is a washing machine and the sealing element (6) is the bellows between the loading port (4) and the door (5).
By means of the present invention, a washing medium that is improved in terms of hygiene is provided by the sealing element (6) containing antimicrobial additive material.

Claims

A washer (1) comprising a body (2), a washing chamber (3) wherein the washing process is performed, a loading port (4) through which the items to be washed are loaded into the washing chamber (3), a door (5) that covers the loading port (4) and a sealing element (6) disposed between the loading port (4) and the door (5) and characterized by the sealing element (6) that is produced from antimicrobial material which is tea tree oil and ethylene propylene diene monomer (EPDM) material.
A washer (1) as in Claim 1, characterized by the sealing element (6) that is produced by using EPDM material of 97 – 97 % by weight and antimicrobial additive material with the ratio of 1 – 3 %.
A washer (1) as in Claim 1 or 2, characterized by the sealing element (6) that is produced from thermoplastic elastomer (TPE) material which is polystyrene / elastomer block copolymer.
A washer (1) as in Claim 1 or 2, characterized by the sealing element (6) that is produced from thermoplastic elastomer (TPE) material which is a thermoplastic vulcanizate (TPV) derived from EPDM and polypropylene (PP).
A washer (1) as in any one of the above claims, which is a dishwasher.
A washer (1) as in any one of the Claims 1 to 4, which is a washing machine.