EP2513370B1

EP2513370B1 - Method for producing antibacterial fabrics

Info

Publication number: EP2513370B1
Application number: EP09799712.6A
Authority: EP
Inventors: Sándor Csaba KISS; Imre Kiricsi; Zoltán KÓNYA; Zita Varga
Original assignee: Szegedi Szefo Zrt
Current assignee: Szegedi Szefo Zrt
Priority date: 2009-12-16
Filing date: 2009-12-16
Publication date: 2014-05-14
Anticipated expiration: 2029-12-16
Also published as: WO2011073697A1; SI2513370T1; EP2513370A1; HRP20140733T1

Description

The invention relates to a method for producing antibacterial fabrics knitted from pre-treated yarn, where the yarn of the fabrics is coated with a substance providing shape-retentivity and preventing fluffing in the course of the pre-treatment, afterwards, the fabrics or the parts of the fabrics are knitted from the coated yarn and, subsequently, softening laundering of the fabrics or of the parts of the thereof is carried out, after this, the further necessary operations known themselves are performed.
It is known that silver possesses antibacterial nature. The antibacterial impact of silver is due to the specific chemical reaction processes arising from its particular characteristics. Owing to the size of nanosilver particles, they are capable to react directly with bacteria, which usually have diameter between 1 nm and 10 nm. The antibacterial impact of nanosilver particles consists in their increased chemical activity in consequence of their large specific surface and, as a result, bacterium cell is damaged, cell wall is injured, and nanosilver particles accumulate in the cell membrane, which results in the death of the cell.
Nowadays, the treatment of fabrics with nanosilver is more and more widespread in case of manufacturing cloths and sanitary commodities in order to reach antibacterial impact. When knitted fabrics are aimed to be fabricated, nanosilver particles are attached to the fibres of yarn before knitting. Such solution can be known from the international patent application by Yan et al., of publication number WO03/080911 , titled as "Antimicrobial yarn having nanosilver particles and methods for manufacturing the same". The disadvantage of this solution is that it is not applicable for fabrics made from more precious yarn. Namely, in case of fabrics made from more precious yarn, the yarn is pre-treated before knitting, that is, it is coated with a substance providing shape-retentivity and preventing fluffing. Such coating, however, inhibits application of nanosilver on the yarn in the way described in the above patent specification. Further disadvantage of that solution is that the whole yarn surface is covered uniformly with nanosilver, therefore significantly more silver is used than it is necessary to achieve the goal at knitted fabrics worn as upper clothes. A further disadvantage of that solution is that the yarn to be knitted is coated with nanosilver, as a consequence of which large silver loss may be produced at knitting.
In the publication of database WPI week 200806 Thomson Scientific, London GB; AN 2008-A92269 & KR 2007 0005108 A (Son M. H.) 10 January 2007 a method for producing antibacterial fabrics is disclosed. The surface of the fabrics are sprayed with sodium palmitate surfactant, and then immersed with a liquid containing silver nanoparticules. The disadvantages of this method are that by means of spraying the surfactant will not reach the surface of the knitted fabrics uniformly, on the other hand by means of the disclosed technology the precipitation of the silver nanoparticles can not be satisfactory, and the technology is not simple enough, it can not be made within one step. The following documents belonging also to the state of the art show the same problems, such as: publication of database WPI week 200631 Thomson Scientific, London GB; AN 2006-295613 & CN 1 702 232 A (Univ. Res. Inst. Tsinghua in Shenzhen) 30 November 2005, furthermore patent specification US 2007/0003603 A1, Bhalchandra M. Karandikar et al, 4 January 2007 , and article of Langmuir 1998, Vol. 14, p. 602-610, Wang W et al: "Directing oleate stabilized nanosized silver colloids into organic phases".
The goal of the invention is to eliminate the mentioned disadvantages and, thus, to provide a method that can be also applied in case of fabrics knitted from more precious yarns for upper clothes, where the fabrics are knitted from yarn coated with substance providing shape-retentivity and preventing fluffing. It is to be noted that such fabrics are laundered less frequently than underwear or medical robes, moreover, that there is no need to entirely saturate the fabrics with silver, but silver coating is essential on the parts of the clothes close to the body-surface.
The invention is based on the recognition that the fabrics or the parts of the fabrics knitted from yarn which were coated with substance - favourably with paraffin wax -providing shape-retentivity and preventing fluffing are treated to achieve their antibacterial property during or after their softening laundering in such a way that an alkaline salt of a saturated or unsaturated organic acid with long carbon chain, as a sufactant, silver salt and, then, a reducing agent and sodium carbonate are added to the laundering or to the soaking water. It is observed that alkaline salts of organic acids with long carbon chain, especially sodium salts of saturated or unsaturated fatty acids, mainly sodium palmitate, sodium oleate, sodium linoleate and sodium stearate, promote the binding of nanosilver particles on the yarn probably by absorption interaction between the coating on the yarn and the nanosilver particles, and thus, fixing the nanosilver on the yarn.
Our invention provides a suitable method for producing antibacterial fabrics from pre-treated yarn, where the yarn of the fabrics is coated with a substance providing shape-retentivity and preventing fluffing in the course of the pre-treatment, afterwards, the fabrics or the parts of the fabrics are knitted from the coated yarn and, subsequently, softening laundering of the fabrics or of the parts of the thereof is carried out, after this, the further necessary operations known themselves are performed. The fabrics or the parts of the fabrics knitted from the yarn which were coated with the substance providing shape-retentivity and preventing fluffing are also washed and/or soaked during or after their softening laundering in such a washing water, during and/or after their softening laundering, to which a surfactant or its solution in water, a silver salt or its solution in water, and then a reducing agent or its solution in water and sodium carbonate or its solution in water is added.
It seems as the surfactant or tensid can loosen the coating composed from substance - favourably from paraffin wax -providing shape-retentivity and preventing fluffing, and makes the surface of the yarn suitable to receive silver.
The operations known themselves mentioned earlier are usually the following varying depending on the yarn material as well: centrifuging at 500-800 rpm, drying usually below 80°C, favourably at temperature of 50-60°C, control of fabrics or the parts of fabrics, in case of parts of fabrics their assembly into ready-to-wear cloths, then, ironing of the semi-finished cloths, final sewing, ironing of the finished ready-to-wear cloths.
According to a preferred implementation of the invention, sodium salts of saturated or unsaturated fatty acid are used as alkaline salts of a saturated or unsaturated organic acid with long carbon chain, especially at least one of the following: sodium palmitate, sodium oleate, sodium linoleate and sodium stearate.
According to a further preferred implementation of the invention, the quantity of the added sodium salt of fatty acid is chosen at a ratio of 5-6.5 compared to the quantity of the added silver.
According to a further preferred implementation of the invention, the quantity of the added reducing agent is chosen at a ratio of 1-2, preferably at a ratio of 1.2, compared to the quantity of the added silver.
According to a further preferred implementation of the invention, the quantity of the added sodium carbonate is chosen at a ratio of 0,25-1, preferably at a ratio of 0.5-0.75, compared to the quantity of the added silver.
According to a further preferred implementation of the invention, at least one of the following compounds is applied as silver salt: silver nitrate, silver acetyl acetonate, silver sulphate.
According to a further preferred implementation of the invention, the concentration of silver in the washing water is set at 10-500 ppm, preferably at 10-200 ppm, the most preferred range is 20-80 ppm.
According to a further preferred implementation of the invention, the ratio of the weight of the silver fed into the washing water is set in a range between 1:500 and 1:2000 compared to the weight of the fabrics.
According to a further preferred implementation of the invention, the ratio of the washing water with the additives and the fabric is between 5-50, preferably 10-15, by weight.
According to a further preferred implementation of the invention, at least one of the following compounds is applied as reducing agent: ascorbic acid, D-glucose, hydroxyl amine, sodium borohydride.
According to a further preferred implementation of the invention, paraffin wax is applied as substance providing shape-retentivity and preventing fluffing.
According to a further preferred implementation of the invention, the washing and the soaking processes are performed in a washing machine, altogether for 3-50 minutes, preferably for 8-30 minutes.
The above described implementations can be applied for the most varied yarns, but the implementations are recommended for yarns containing at least one of the following materials: wool, cotton, silk.
Benefits gained by using the invention are the following. Coating of fabrics with nanosilver layer becomes possible for pre-treated, coated fabrics, for example fabrics treated with paraffin wax and, thus, making clothes knitted from more precious yarn, for example from wool, cotton and silk, antibacterial. There is no silver loss during knitting. Further benefit is the simplicity of the production technology, as additional technological steps are not needed for coating with nanosilver layer since it can be implemented in the same phase as the softening laundering being part of the conventional technology.
At the fabrics produced with the process according to the invention, the nanosilver coating created to achieve antibacterial nature is usually present unevenly, that is, to a larger extent on the surface areas, whereas to a lesser extent in the elementary fibres, which means no disadvantage in case of upper wear, but less silver is consumed thus than in case of coating the yarn when its surface and inside of the elementary yarn is coated evenly.
Hereinafter, our invention is demonstrated on examples in details without the aim of limiting the scope of our solution thereto, since, within the patent scope, manifold variations are possible for the implementation of the invention in addition to the demonstrated examples.

Example 1: Fabric parts or pieces knitted from pre-treated with paraffin wax yarn are laundered in water at temperature 30°C containing softener Softin™ available from wholesale trade. 0,25 litre Softin™ softener was dissolved in 100 litres of water. The next operation is the ironing of the semi-finished fabric pieces. The main ingredient of the applied softener is carboxyethyl-hydroyethylmethylammonium-methosulphate, CAS number: 91 995-85-2. Hereupon 4 kg of fabric pieces were immersed in washing water at 30°C, then solution of sodium oleate in washing water at concentration of 0,17391 g/litre was added as sodium salt of surface active fatty acid, finally silver nitrate solution in water at concentration of 0,05478 g/litre. The fabric pieces were properly rotated in the washing machine. Subsequently ascorbic acid solution in water at concentration of 0.06817 g/litre was added as reducing agent, where 20 % surplus quantity of ascorbic acid was in relation to the quantity of the silver. Moreover, sodium carbonate solution in water at concentration of 0,04348 g/litre was added. Using the above compositions concentration of silver was set at about 28 ppm in 140 litres washing water. Fabric pieces were properly laundered for 50 minutes alternating rotating and soaking steps, then they were centrifuged and further in itself known operations were performed.
Example 2: Fabric parts or pieces knitted from pre-treated with paraffin wax yarn are laundered in water at temperature 30°C containing softener Softin available from wholesale trade. 0,25 litre Softin softener was dissolved in 100 litres of water. The next operation is the ironing of the semi-finished fabric pieces. Hereupon 10 kg of fabric pieces were immersed in washing water at 30°C, then solution of sodium oleate in water at concentration of 0,27826 g/litre was added as sodium salt of surface active fatty acid, finally silver nitrate solution in water at concentration of 0,08765 g/litre was added to it. The fabric pieces were properly rotated in the washing machine. Subsequently ascorbic acid solution in water at concentration of 0,10908 g/litre was added as reducing agent, where 20 % surplus quantity of ascorbic acid was in relation to the quantity of the silver. Moreover, sodium carbonate solution in water at concentration of 0,06957 g/litre was added. Using the above compositions concentration of silver was set at about 56 ppm in 115 litres washing water. Fabric pieces were properly laundered for 8 minutes alternating rotating and soaking steps, then they were centrifuged and further in itself known operations were performed.
Example 3: About 10 kg of fabric parts or pieces knitted from pre-treated with paraffin wax yarn were immersed in washing water at 30°C. Then softener Softin available from wholesale trade was added as in the above examples and solution of sodium oleate in water at concentration of 0,21818 g/litre was added as sodium salt of surface active fatty acid, finally silver nitrate solution in water at concentration of 0,06873 g/litre was added to it. The fabric pieces were properly rotated in the washing machine. Subsequently ascorbic acid solution in water at concentration of 0,08553 g/litre was added as reducing agent, where 20 % surplus quantity of ascorbic acid was in relation to the quantity of the silver. Moreover, sodium carbonate solution in water at concentration of 0,05455 g/litre was added. Using the above compositions concentration of silver was set at about 44 ppm in 110 litres washing water. Fabric pieces were properly laundered for 14 minutes alternating rotating and soaking steps, then they were centrifuged and further in itself known operations were performed.
Example 4: Fabric parts or pieces knitted from pre-treated with paraffin wax yarn are laundered in water at temperature 30°C containing softener Softin available from wholesale trade. Softin™ softener was diluted as in the above examples. The next operation is the ironing of the semi-finished fabric pieces. Hereupon 10 kg of fabric pieces were immersed in washing water at 30°C, then solution of sodium oleate in water at concentration of 0,36364 g/litre was added as sodium salt of surface active fatty acid, finally silver nitrate solution in water at concentration of 0,11455 g/litre was added to it. The fabric pieces were properly rotated in the washing machine. Subsequently ascorbic acid solution in water at concentration of 0,142545 g/litre was added as reducing agent, where 20 % surplus quantity of ascorbic acid was in relation to the quantity of the silver. Moreover, sodium carbonate solution in water at concentration of 0,09091 g/litre was added. Using the above compositions concentration of silver was set at about 73 ppm in 110 litres washing water. Fabric pieces were properly laundered for 14 minutes alternating rotateing and soaking steps, then they were centrifuged and further in itself known operations were performed.
Example 5: 10 kg of fabric parts or pieces knitted from pre-treated with paraffin wax yarn were immersed in washing water at 30°C. Then softener Softin available from wholesale trade was added as in the above examples and solution of sodium oleate in water at concentration of 0,45455 g/litre was added as sodium salt of surface active fatty acid, finally silver nitrate solution in water at concentration of 0,14318 g/litre was added to it. The fabric pieces were properly rotated in the washing machine. Subsequently ascorbic acid solution in water at concentration of 0,17818 g/litre was added as reducing agent, where 20 % surplus quantity of ascorbic acid was in relation to the quantity of the silver. Moreover, sodium carbonate solution in water at concentration of 0,11364 g/litre was added. Using the above compositions concentration of silver was set at about 91 ppm in 110 litres washing water. Fabric pieces were properly laundered for 14 minutes alternating rotating and soaking steps, then they were centrifuged and further in itself known operations were performed.
Example 6: Fabric parts or pieces knitted from pre-treated with paraffin wax yarn are laundered in water at temperature 30°C containing softener Softin available from wholesale trade. Softin™ softener was diluted as in the above examples. The next operation is the ironing of the semi-finished fabric pieces. Hereupon 10 kg of fabric pieces were immersed in washing water at 30°C, then solution of sodium oleate in water at concentration of 0,45455 g/litre was added as sodium salt of surface active fatty acid, finally silver nitrate solution in water at concentration of 0,14318 g/litre was added to it. The fabric pieces were properly rotated in the washing machine. Subsequently ascorbic acid solution in water at concentration of 0,17818 g/litre was added as reducing agent, where 20 % surplus quantity of ascorbic acid was in relation to the quantity of the silver. Moreover, sodium carbonate solution in water at concentration of 0,11364 g/litre was added. Using the above compositions concentration of silver was set at about 91 ppm in 110 litres washing water. Fabric pieces were properly laundered for 14 minutes alternating rotating and soaking steps, then they were centrifuged and further in itself known operations were performed.
Example 7: 10 kg of fabric parts or pieces knitted from pre-treated with paraffin wax yarn were immersed in washing water at 30°C. Then softener Softin available from wholesale trade was added as in the above examples and solution of sodium oleate in water at concentration of 0,57852 g/litre was added as sodium salt of surface active fatty acid, finally silver nitrate solution in water at concentration of 0,14318 g/litre was added to it. The fabric pieces were properly rotated in the washing machine. Subsequently ascorbic acid solution in water at concentration of 0,17815 g/litre was added as reducing agent, where 20 % surplus quantity of ascorbic acid was in relation to the quantity of the silver. Moreover, sodium carbonate solution in water at concentration of 0,11364 g/litre was added. Using the above compositions concentration of silver was set at about 91 ppm in 110 litres washing water. Fabric pieces were properly laundered for 50 minutes alternating rotating and soaking steps, then they were centrifuged and further in itself known operations were performed.
Example 8: 10 kg of fabric parts or pieces knitted from pre-treated with paraffin wax yarn were immersed in washing water at 35°C. Then softener Softin available from wholesale trade was added as in the above examples and solution of sodium oleate in water at concentration of 0,29091 g/litre was added as sodium salt of surface active fatty acid, finally silver nitrate solution in water at concentration of 0,07157 g/litre was added to it. The fabric pieces were properly rotated in the washing machine. Subsequently ascorbic acid solution in water at concentration of 0,08553 g/litre was added as reducing agent, where 20 % surplus quantity of ascorbic acid was in relation to the quantity of the silver. Moreover, sodium carbonate solution in water at concentration of 0,05455 g/litre was added. Using the above compositions concentration of silver was set at about 40 ppm in 110 litres washing water. Fabric pieces were properly laundered for 30 minutes alternating rotating and soaking steps, then they were centrifuged and further in itself known operations were performed.

According to our experience, reactions can be more easily controlled in case distilled water is used.
The antibacterial activity of the fabrics covered with silver was examined in all examples. The following bacteria were inoculated onto agar bed: Staphylococcus aureus (Gram+), Escherichia coli (Gram-), Pseudomonas aeruginosa (Gram-) and Candida albicans fungus. The examinations were made as follows: A sterilised sample of fabric was placed into a Petri dish, about 8 ml of nutrient substratum at 42 C° was layered onto it in thickness of 2-3 mm, then micro-organisms were inoculated onto this solid nutrient substratum. The concentration of the micro-organism suspension was 10⁵ - 10⁶ cells/ml. The test samples were cultured at 30 C° for 24 hours. It has been found that microbial growth of the listed micro-organisms was held down at the samples prepared according to the examples in comparison to those of the fabric samples without silver coating.
According to our observations, the diameter of the nanosilver particles was 8.66 nm on average with ±1,18 nm average deviation, which data were specified based on recordings prepared with Philips CM 10 type transmission electron microscope operating at a voltage of 100 kV.
The antibacterial nature lasts even after at least 5 washing operations, which is enough in case of valuable fabrics for upper clothes, because they do not need frequent laundering.

Claims

A method for producing antibacterial fabrics knitted from pre-treated yarn, where yarn of the fabrics is coated with substance providing shape-retentivity and preventing fluffing in the course of the pre-treatment, afterwards, the fabrics or the parts of the fabrics are knitted from the coated yarn and, subsequently, softening laundering of the fabrics or of the parts of the thereof is carried out, after this, the further necessary operations known themselves are performed, characterized by that the knitted fabrics or the parts of the knitted fabrics knitted from yarn which was coated with substance providing shape-retentivity and preventing fluffing are washed and/or soaked in a washing water to achieve nanosilver coating in such a way that an alkaline salt of a saturated or an unsaturated organic acid with long carbon chain, as a surfactant, or its solution in water, a silver salt or its solution in water and, then, a reducing agent or its solution in water and sodium carbonate or its solution in water are added into the washing water during and/or after the softening laundering.
The method according to claim 1, characterized by that sodium salt of saturated or unsaturated fatty acid is used as alkaline salt of a saturated or unsaturated organic acid with long carbon chain.
The method according to claim 2, characterized by that at least one of the followings is used as sodium salt of saturated or unsaturated fatty acid: sodium palmitate, sodium oleate, sodium linoleate and sodium stearate.
The method according to claim 2, characterized by that the quantity of the added sodium salt of fatty acid is chosen at a ratio of 5-6.5 compared to the quantity of the added silver.
The method according to claim 1, characterized by that the quantity of the added reducing agent is chosen at a ratio of 1-2, preferably at a ratio of 1.2, compared to the quantity of the added silver.
The method according to claim 1, characterized by that the quantity of the added sodium carbonate is chosen at a ratio of 0,25-1, preferably at a ratio of 0.5-0.75, compared to the quantity of the added silver.
The method according to claim 1, characterized by that at least one of the following compounds is used as silver salt: silver nitrate, silver acetyl acetonate, silver sulphate.
The method according to claim 1, characterized by that the concentration of silver in the washing water is set at 10-500 ppm, preferably at 10-200 ppm, the most preferred range is 20-80 ppm.
The method according to claim 1, characterized by that the ratio of the weight of the silver added into the washing water is set in a range between 1:500 and 1:2000 compared to the weight of the fabrics.
The method according to claim 1, characterized by that the ratio of the washing water and the fabric is 5-50, preferably 10-15, by weight.
The method according to claim 1, characterized by that at least one of the following compounds is used as reducing agent: ascorbic acid, D-glucose, hydroxyl amine, sodium borohydride.
The method according to claim 1, characterized by that paraffin wax is used as substance providing shape-retentivity and preventing fluffing.
The method according to claim 1, characterized by that the washing and the soaking processes are performed in a washing machine during 3-50 minutes, preferably during 8-30 minutes.
The method according to claim 1, characterized by that the yarns should contain at least one of the following materials: wool, cotton, silk.