Mahltig, et al., J Fashion Technol Textile Eng 2015, 3:1 http://dx.doi.org/10.4172/2329-9568.1000118 Research Article Copper Containing Coatings for Metallized Textile Fabrics Boris Mahltig1*, Daniel Darko1, Karoline Günther1 and Hajo Haase2,3 Abstract Compared to silver modified textiles, textiles modified with copper components are less prominently mentioned in literature. Therefore, the aim of the now presented paper is to present an overview on different copper functionalized textiles. For this presentation, two types of fabrics are taken into account – commercially available copper plated polyamide and textiles coated with copper containing effect pigments. The surface properties and the composition of those materials are presented in detail. Optical properties are determined in the arrangements of diffuse reflection and diffuse transmission for UV-, visible- and IR-light. Hints on probable applications in the fields of radiation protection are reported. Furthermore, antibacterial properties against the bacteria E.coli and S.aureus are reported. In most cases, copper is accompanied by different types of metals (such as silver, zinc, aluminium or nickel) or semi-metal (as silicon) and the material properties and antibacterial activity are significantly influenced by these accompanying elements. Copper coated textiles are promising for realization of optical effects, electric conductive fabrics, radiation protection and antimicrobial applications. Keywords Metallized textiles; Antimicrobial; Conductive; Surface modification Introduction Copper is used by humans since ancient times for many purposes as household devices, tools, weapons or coins [1-3]. This red metal has the second highest electric conductivity, high thermal conductivity and also antimicrobial properties [4,5]. Compared to the other two metals of the same family, silver and gold, the price of copper is moderate (Table 1) [6]. However for many applications copper is not used as pure element. The surface of copper is often coated to prevent corrosion and oxidation from air and rain leading to undesired color shades [7,8]. Also copper is used as alloy (bronze) to decrease its softness or to reach special optical color shades from dark red to bright yellow [9]. Altogether copper is an interesting and useful metal, whose useful properties can be combined with textiles by application of copper containing coatings. Very prominently described in the literature are silver coated textiles, probably because of their high electric conductivity, their antimicrobial activity and manifold applications in the medicine [10-16]. Due to the rise of nanotechnology in recent *Corresponding author: Boris Mahltig, FTB, Hochschule Niederrhein – University of Applied Sciences, Faculty of Textile and Clothing Technology, Webschulstr. 31, 41065 Mönchengladbach, Germany, Tel: +49 2161 186 6128; Fax: +49 2161 186 6013; E-mail: [email protected] Received: August 30, 2015 Accepted: December 23, 2015 Published: December 27, 2015 International Publisher of Science, Technology and Medicine Journal of Fashion Technology & Textile Engineering a SciTechnol journal years, also many reports are related to the application of silver nanoparticles onto textiles [17-22]. However, it should be mentioned that products containing silver and especially nanosilver are a topic in public discussions, because environmental and health risks are expected. With background of these discussions many companies also search for alternative silver-free materials with same quality and property but less public recognition. Suitable alternatives could be given by other metals in the same chemical family - copper or gold. As noble metal also gold is reported for application onto textile substrates. These applications are performed as coating through electroless deposition and by application of gold nanoparticles. The purpose of the gold coatings is to realize electric conductive fibers. By application of gold nanoparticles beside the modification of the elelctrostatic properties also optical properties, UV-protection and antimicrobial functions are introduced onto the textile substrates [2325]. However due to the costs of gold as metal or gold compounds used as precursors for those preparations, it is from the economic point of view not clear, if such applications will ever be commercialized in a broad range of daily life applications. Compared to the large number of reports on silver coated textiles, textiles coated with copper are rarely discussed in literature. Copperplated fabrics are realized by electroless plating with the aim to create a textile material for electromagnetic interference shielding (EMI shielding) [26,27]. The combination of copper plating together with other metals leads to different alloy containing coatings on textiles. By this, different types of metallic coloration are realized for fashion [28]. Beside EMI-shielding and coloration a very important issue is the realization of fabrics or yarns with electric conductivity by coating with copper [29,30]. Applications for these materials can be even found in the field of medical devices, e.g. conductive copper plated polyester fabrics for EEG measurement [31]. Beside the preparation by electroless plating also different types of sputtering techniques and vacuum evaporation deposition technique are used to realize copper coatings on textiles and yarns [32-35]. These reported examples are mainly from scientific background and related to the excellent conductivity of copper and applications for EMI-shielding. For this, one aim of the now presented study is to report on the antimicrobial properties of commercially available materials as coated textiles plated by copper containing material and textiles coated with a composition containing a binder and copper containing effect pigments. Effect pigments are anisotropic pigments with outstanding reflectivity for realization of special optical effects [36]. These effect pigments can be used in textile coatings as well [37]. In general it can be distinguished between metal oxide containing effect pigments and those effect pigments based on pure metal or alloy [38-40]. Silver pigments are often used for printing of electrical circuits, copper pigments to gain electric conductivity and gold bronze pigments for special optically effect gold shades [9]. The comparison of copper plated and effect pigment containing coatings is the aspect of this current paper, especially with respect to the antimicrobial activity and optical properties of the investigated textile materials. The determined properties are set in relation to composition, structure and preparation process of the investigated coated fabrics. All articles published in Journal of Fashion Technology & Textile Engineering are the property of SciTechnol, and is protected by copyright laws. Copyright © 2015, SciTechnol, All Rights Reserved. Citation: Mahltig B, Darko D, Günther K, Haase H (2015) Copper Containing Coatings for Metallized Textile Fabrics. J Fashion Technol Textile Eng 3:1. doi:http://dx.doi.org/10.4172/2329-9568.1000118 Metal Prize [Euro/kg] Gold 28650 – 32590 Silver 431 – 503 Tin 17.1 – 17.2 Nickel 13.9 – 14.0 Copper 5.0 – 5.1 Table 1: Overview on different industrially used metals and costs as reported by an economic newspaper in spring 2015 [6]. Materials and Methods Materials and sample preparation Two types of copper containing textiles are taken into account for the current investigation. First, these are plated polyamide fabrics from the company Statex Produktions+Vertriebs GmbH (Bremen, Germany). The purpose of these materials is mainly for EMI-shielding and to support an electric conductive textile. Types and names of these polyamide fabrics are listed in Table 2. According to the product information gained from the supplier the polyamide type A; B and C also contain other metals besides copper. This difference in metal composition significantly influences the color of the fabric. Polyamide type D contains as metal only silver and is used as reference. The effect pigment coated textile substrates are realized by coating of three different types of textiles (cotton, polyester, cotton 65%/ polyester 35% blend) with three different types of copper containing effect pigments supplied by the company Eckart GmbH (Hartenstein, Germany). The textiles are plain woven materials with the weight of 192 g/m2 for cotton (green colored), 82 g/m2 for polyester (white colored) and 215 g/m2 for the cotton/polyester blend (black colored). All used effect pigments are containing copper. Two of them are gold bronze pigments containing copper alloy with the purpose of advantageous optical effects. The third pigment is named econduct and consists of a silver coated copper flake to realize electric conductive coatings. Detailed informations are summarized in Table 3. Altogether a sample set of nine different samples are taken into account for this investigation. An acrylate binder of the type “Printperfekt 226 EC” supplied by the CHT Beitlich GmbH (Tübingen, Germany) is used to fix the pigments on the fabrics. This is a white acrylate screen printing paste in an aqueous solution based on a dispersion of polyacrylates. The pH of this Printperfekt-type is 7.5 to 9 and the solid content is 10 %. For printing application a mixture of binder:water:effect pigment is used in a ratio of 3:1:1. The printing paste is applied by flat screen printing using a screen with the mesh hole of approximately 40 μm. After printing, the sample was dried and fixed at 100°C for 5 minutes. Analytical methods Material analytics: For investigation of the surface topography of coated samples scanning electron microscopy (SEM) is used. These measurements are performed with a TM 3000 Tabletop microscope from Hitachi. For all SEM measurements, the acceleration voltage is set to 15 kV. The SEM device is equipped with an EDS unit (energy dispersive spectroscopy) Quantax 80 from Bruker, which enables the determination of the elemental composition on sample surfaces. With this EDS-device the chemical elements on the sample surface can be detected, if the content of the element is 0.1 wt-% or higher. The detection of the element nitrogen by EDS is for textile samples almost difficult, because of the high content of carbon and the similarity of peak position in the EDS spectrum of carbon and nitrogen signal. The EDS-method is especially used for the element Volume 3 • Issue 1 • 1000118 determination of the investigated metallized textiles, because this method enables determining the element composition on the surface of the samples and metallic coatings are the subject of the paper. The optical properties of the textile samples are determined in arrangement of diffuse reflection and transmission in a spectral range from UV light to near infrared light (220 nm to 1400 nm). For this, a spectrophotometer ISR-2600 Plus was used. This device contains an integrating sphere allowing the detection of diffuse light. As reference for this optical measurement a barium sulphate white standard was used. The electric surface resistance of the samples containing metallic effect pigments are determined with a testing device MilliTO3 supported by “Fischer Elektronik GmbH”. The electromagnetic shielding properties of effect pigment containing samples were tested by using a “Spectrum HF-6085X Analyser” equipped with an OmniLOG antenna supported by AaroniaAG. As transmitter in this arrangement a T868-K2 with a frequency of 868 MHz was used. Antibacterial analytics: Antimicrobial testing is done by a viability assay based on the reduction of methylthiazolyldiphenyltetrazolium bromide (MTT) as described elsewhere [41,42]. Briefly, two types of bacteria, E. coli and S. aureus were grown for 3h at 37°C, rotating at 120 rpm in an orbital incubator, in the presence of textile samples (squares of 5 mm edge length) in sterile 96-multiwell cell culture plates. Subsequent to treatment with the fabric samples cells were incubated with 0.01% (w/v) MTT in culture medium, followed by lysis in isopropanol and determination of the absorption at 570 nm with a reference wavelength of 700 nm. For each textile sample the measurement was conducted three times with different cutouts from the same sample. A viability value of 100% stands for a bacterial viability in a test arrangement without any textile fabric. Additional reference measurements are performed with three different types of uncoated polyamide fabrics. Also uncoated polyester, cotton and cotton/polyester blended fabrics were used for reference measurements as wells as the same type of fabrics coated with pure binder layer without any addition of metallic pigments. Results and Discussion Materials and surface properties The element composition of the plated polyamide fabrics are determined by EDS-method and compared to the information gained by the manufacturer (Tables 2 and 4). The related EDS-spectra are depicted in Figure 1. From the spectra, it is clear that elements detected with a small content of 0.2 wt-% are nearly at the borderline of the resolution of the methods. Fabric type A is named as copper, tin and silver plated fabric and also all these metals are detected by EDS. However the silver content is quite small with only 0.2 wt-%. The copper content is with values >60 wt-% the highest. The elements carbon and oxygen are only determined in small amounts. These results indicate that the metal coating nearly completely covers the textile surface. Also the formation of metal oxide on the coating surfaces could not be determined. According to supplier information, fabric type B is plated with a composition of copper and silver. However by EDS-method only copper can be determined on the sample surface. The absence of silver in the EDS-spectrum could be explained by low a small content of <0.1 wt-% silver or the silver is not directly present on the surface of the coating. An explanation could be that silver is applied in small amounts in a first coating step and in a second process step the larger amount of copper is deposited. • Page 2 of 10 • Citation: Mahltig B, Darko D, Günther K, Haase H (2015) Copper Containing Coatings for Metallized Textile Fabrics. J Fashion Technol Textile Eng 3:1. doi:http://dx.doi.org/10.4172/2329-9568.1000118 Table 2: Overview of investigated metallized polyamide fabrics, composition, purposes and properties are given according to producer information. Type No. Trade name Composition Purpose Color Plain weight [g/m2] Surface Shielding effectiveness resistance [Ohm] A Zell RS Tin coppersilver plated nylon fabric Conductive woven fabric for general use Light grey 77 0.02 80 dB from 300 Mhz to 10 Ghz B Kassel RS Copper-silver plated nylon Conductive gasket skin Red 93 0.03 80 dB from 300 Mhz to 3 Ghz C Nora Dell DR Nickel /copper / silver platednylon fabric Conductive woven fabric for general use Grey 95 0.09 100 dB from 30 Mhz to 10 Ghz D Berlin RS Silver plated nylon fabric; PUR coating on one side Conductive fabric for gasket skin black 50 0.3 60 dB from 300 Mhz to 3 Ghz Table 3: Overview of investigated metal effect pigments, used as additives in textile coatings. Pigment No. Trade name Composition Purpose P1 Shinedecor 9350 Goldbronze Advanced optical effects Color Red P2 Shinedecor 9355 Goldbronze Advanced optical effects Yellow P3 Econduct 421000 Silver coated copper Conductive effects Pale red Table 4: Element composition on the plated polyamide fabrics as determined by EDS-method, magnification with 1500X; Only elements with a content of 0.1 wt-% or higher are recorded. Type No. Detected metals [wt-%] Detected non-metals and semi-metals [wt-%] Cu Ni Sn Ag C O P Si A 67.8+/-2.1 --- 26.4 +/-0.8 0.2 +/-0.1 4.7 +/-0.6 0.8 +/-0.1 --- ----- B 47.4+/-1.6 --- --- --- 41.5 +/-4.6 11.1 +/-1.3 --- C 22.1+/-0.7 27.6 +/-0.9 --- --- 39.3 +/-4.4 7.9 +/-0.9 3.3+/-0.2 --- D --- --- --- 28.3 +/-0.8 51.4 +/-4.8 20.2 +/-2.1 --- 0.2+/-0.1 For polyamide fabric type C the situation is similar. The supplier stated a coating containing the metals copper, nickel and silver. However silver was not detectable by EDS-method, while the metals copper and nickel are present in a ratio nearly 1:1. Surprisingly also the element phosphor is detected on type C with the significant content of 3.3 wt-%. The presence of phosphor could be the result of production process. For some electroless deposition processes the addition of phosphor containing compounds, such as sodium hypophosphite is reported [29]. The fabric type D contains as expected silver in a high amount of >25 wt-%. No further other metal is detected on type D, additionally only small amounts of 0.2 wt-% silicon can be observed. The surface topography of the electroplated polyamide fabrics is investigated by SEM and for example the SEM images of fabric type A are presented in Figure 2 with increasing magnification. It can be seen that the coating is very flat and evenly distributed. In higher magnification of 12000X a porous structure of the metal coating gets visible. On the pigment containing samples, by EDS-method different types of metal and semi-metal beside copper are detected (Figure 3 and Table 5). With pigment P1 beside copper only silicon is determined. It is known that copper surfaces will oxidize with air during time and by this a color change to black or green occurs. In fact, this type of color change is not wished for copper based effect pigments, so usually they are coated to protect the copper surface. Usual such a coating can be of organic nature but also silicon containing coatings are in use [7,8]. Other metals are not detected by EDS-method for pigment P1, even if for gold bronze pigments additional metals should be expected. However with EDS-method only elements with content higher >0.1 wt-% are taken into account due to the accuracy of this method. Samples with pigment P2 contains beside copper and silicon also the metals aluminium and zinc in significant amounts. The presence of these metals is obvious a requirement to gain the “goldenVolume 3 • Issue 1 • 1000118 yellow” coloration of this gold bronze pigment. The coatings with pigment P3 contains beside copper also silver. This is in accordance to the product information supplied by the pigment producer, that this pigment is a silver coated copper based pigment. The evaluation of surface topography of the textiles with pigment containing coating is done by SEM (Figure 4). It is seen that the pigment particles are regularly distributed over the whole textile surface and that the single effect pigments contain the socalled “cornflake”-structure. This cornflake structure is typical for effect pigments and results from the production process. It is also determined that mostly the anisotropic effect pigments are oriented parallel to the textile surface. This is reported earlier to be the result of a self-orientation during the coating and drying process [43]. Optical properties and radiation protection The optical properties are determined for all samples in the spectral range of 220 nm to 1400 nm and give for this information on the coloration of samples but also on their ability to support protection against UV- and IR light. These measurements are performed in arrangement of diffuse reflection especially to support coloration information and in diffuse transmission to support information concerning radiation protection. In the measurement arrangement of diffuse transmission all light which is transmitted through the sample is collected and summarized. In comparison to the common transmission measurements, in case of the actually used arrangement beside the direct transmitted light also the light scattered during the transmission is detected. The optical spectra of the plated polyamide fabrics are summarized in Figure 5. In the visible range of light the reflection spectra are according to the color of the fabric. The fabric types A, C and D are grey with increasing intensity, so their reflection should be of same intensity in the visibile range. For type A the reflection is in the range of 30% to 40% for visible light. For the type C and D the reflection is around 20%. In the IR-range the reflection is little higher while for the UV-range reflection is lower, with values • Page 3 of 10 • Citation: Mahltig B, Darko D, Günther K, Haase H (2015) Copper Containing Coatings for Metallized Textile Fabrics. J Fashion Technol Textile Eng 3:1. doi:http://dx.doi.org/10.4172/2329-9568.1000118 Figure 1: SEDS-spectra of the different metallized fabric types; the EDS is performed during SEM measurements with magnification of 1500x. of around 5% for polyamide type C. The step determined in spectrum of type A at wavelength of 830 nm is caused by changing of detectors at this wavelength in the chosen arrangement of measurements. A significant different reflectance spectrum is determined for polyamide type B which contains the typically copper red coloration. This type B exhibits significantly higher reflectance values for red visible light and infrared light up to 80% reflection values. Figure 2: SEM-images of increasing magnification metallized polyamide fabric type A. Volume 3 • Issue 1 • 1000118 The reflection spectra give mainly information on the color properties of the samples. In comparison the transmission spectra give information on the properties of textile samples to protect against radiation. For this case, all four polyamide samples exhibit excellent values with diffuse transmission of smaller 5% over the whole investigated spectral range from 220 nm to 1400 nm (Figure 5). For this, a radiation protection can be stated for UV-light and near infrared light. The fabric types A, B and C with pure metallic coating exhibit nearly the same transmission in the IR-area, however the type B gives lower transmission values for the UV-range. This red colored polyamide sample type B with pure copper coating seems to be especially suitable for a absorption of UV-light and therefore for UV protective applications. In contrast to the other investigated • Page 4 of 10 • Citation: Mahltig B, Darko D, Günther K, Haase H (2015) Copper Containing Coatings for Metallized Textile Fabrics. J Fashion Technol Textile Eng 3:1. doi:http://dx.doi.org/10.4172/2329-9568.1000118 transmission. Also these samples exhibit a strong shielding for electromagnetic radiation in the range of 300 Mhz to 3 Ghz (Table 2). Altogether it can be summarized that the presented metallized polyamide fabrics are excellent materials for applications of radiation and light protection. They enable the protection against different types of radiation from UV-light to microwaves. The reflection spectra of the pigment coated fabrics are presented in Figure 6. It is shown that the reflectance in the IR-area is increased on the polyester substrate and the cotton/polyester blended yarn by the applied effect pigments. For the coated cotton fabric the reflection of IR-light is nearly in the same range for coated and uncoated substrate. For this, it can be stated that the effect pigments have a certain property to reflect infrared-light. This property could be of certain interest for applications using heat reflection, e.g. for isolation of buildings. The change in reflection properties in the visible range after application of the effect pigment coatings is related to color changes of the coated substrates, which gain the color of the metallic pigment after the coating application. The spectra of diffuse transmission of those coated fabrics are reported in Figure 7. The transmission spectra are only reported for the substrates cotton and polyester, because the black polyester/cotton blended fabric exhibits already by itself a transmission near zero. It is obviously clear that by effect pigment coatings the transmission of light is reduced significantly over the whole investigated range from 220 nm to 1400 nm. The strongest decrease is gained with coatings containing the pigment P3. Beside the type of applied pigment also the type of textile substrate has a significant influence on the transmission. For the UV-range only on cotton substrate a sufficient low transmission of smaller 5% can be reached by the pigment coatings. On the polyester substrates the transmission for UV-light in the range of 300 nm to 400 nm cannot be decreased to values below 10%, this is probably not enough to indicate a complete protection against the UV-light. Figure 3: EDS-spectra of polyester fabrics carrying a coating with different effect pigments; the EDS is performed during SEM measurements with a magnification of 1500x. polyamide fabrics the fabric type D exhibits no transmission of light in the investigated spectral range. This sample contains beside the metallic silver coating also a coating of black colored polyurethane on one side. This black coating obviously blocks the complete Volume 3 • Issue 1 • 1000118 Textiles coated with coatings containing the pigments P1 and P2 do not contain any shielding property against EMI radiation at 876 MHz. This result is in good agreement with the high surface resistance of >108 Ohm of those samples. Probably these copper effect pigments are coated with inert and isolating material to prevent corrosion of the pigment. These isolating layers causes higher surface resistance, because the pigments are isolated from each other. However for EMI-shielding the textile materials should contain a certain electrical conductivity. In contrast, the pigment P3 contains a copper core and a coating made from conductive silver. The determined surface resistance of P3 coatings on the different textile substrates leads to values of 1.5 X 102 Ohm or smaller, so those coatings create a conductivity on the coated textiles. Analogously to the conductivity of samples also EMI-shielding properties in the range of 60 dB to 65 dB are determined. For this, it should be concluded, that coatings with effect pigment P3 might by useable in the same kind for radiation protective applications as the electroplated polyamide fabrics. In contrast, samples containing the pigments P1 or P2 should be more recommended for usage in decorative and fashion applications. Biocidal properties The antimicrobial effect of copper plated polyamide textiles is tested with bacteria E.coli and S.aureus in reference to three types of different uncoated polyamide textile sample R1, R2 and R3 (Figure 8). The remaining bacterial viability without any textile sample is set as 100% value and the reference samples R2 and R3 lead to nearly the same values. However, the reference R1 leads to a small decrease • Page 5 of 10 • Citation: Mahltig B, Darko D, Günther K, Haase H (2015) Copper Containing Coatings for Metallized Textile Fabrics. J Fashion Technol Textile Eng 3:1. doi:http://dx.doi.org/10.4172/2329-9568.1000118 Table 5: Element composition on coated polyester fabric with coatings containing the different types of metal effect pigments. The element composition is determined by EDS on SEM images with magnification of 1500X; Only elements with a content of 0.1 wt-% or higher are recorded. Type No. Detected metals [wt-%] Detected non-metals and semi-metals [wt-%] Cu Zn Ag Al C O Si P1 25.8+/-0.8 --- --- --- 57.6 +/-5.5 15.3 +/- 1.5 1.3 +/- 0.1 P2 10.9+/-0.3 4.1 +/-0.2 --- 0.2 +/-0.1 65.1 +/-6.4 19.0 +/- 2.0 0.9 +/- 0.1 P3 59.5+/-1.9 --- 4.2 +/-0.2 --- 30.8 +/-3.3 5.5 +/- 0.6 0.4 +/- 0.1 Figure 4: SEM-images of effect pigment coatings on polyester fabrics. The images are shown in increasing magnifications. of bacterial viability to values of around 80%. This result could be explained by effects from remaining finishing agents or dyeing agents inducing an interaction with the bacteria. The coated polyamide fabrics type A and type C are mainly in the same range of remaining bacterial viability as the reference R1. For this, the antibacterial effect as caused by the metal coating could be supposed as measurable but also as very low effect. Remarkable is the comparison, with the fabric type B a certain decrease in bacterial viability to values around 30% are reached, even if the type B do not contain any silver compared to type A. However type B contains a pure copper coating and this is of obviously higher antibacterial activity compared to the alloy coatings which are present in type A and type C. The both fabrics type A and type C carry coatings of copper alloys with tin or nickel. Tin and nickel have as pure elements smaller antimicrobial activity compared to copper, so from coating composition this effect could be expected. Further, Zhu et al. reported the antibacterial properties of different copper alloys against different germs [44]. In this reference it is stated that the investigated copper alloys contain mostly less antibacterial activity compared to pure copper metal. Only few alloys show the same antibacterial activity as pure copper, however these alloys are of highest copper content. Also the amount of silver in type A is very small, so the influence of silver on the antibacterial properties of type A should be also small. The sample D containing the higher silver content is as expected also of strongest determined antibacterial activity. However, the remaining bacterial viability of E.coli is with values around 15% not really low compared to silver containing samples investigated with the same method earlier [15,42]. A possible explanation would be that in type D the silver coating is present in a combination with a polyurethane coating, which could possibly block the release of antimicrobial Volume 3 • Issue 1 • 1000118 active silver ions from the coating. Compared to earlier reports on the antimicrobial effect of copper containing textiles, the copper plated fabrics exhibit lower antimicrobial effect. Reports on strong antimicrobial effects are often related to copper oxide nanoparticles or copper salts applied on the textile [45,46]. These copper containing compounds release copper ions in higher amounts into the surrounding medium and therefore a higher antimicrobial effect can be supposed compared to a metallic copper surface. For investigation of antibacterial properties of the pigment coated textile samples it is absolutely necessary to use as reference beside the uncoated textiles also textile samples coated with pure binder layer without addition of any pigment (Figure 9). It is clearly seen that samples containing the binder coating contain lower remaining bacterial viability, so a certain antibacterial effect could be also expected even for the pure binder layer. This behavior could be explained by residues of biocidic compounds in the binder recipe. Often water-based binder systems, as the one used here, are containing biocides to prevent the binder from bio-contamination and guarantee a longer life-time of the binder recipe. For samples coated with pure binder for E.coli the remaining bacterial viability is in the range of 45% (for CO/PET fabrics) to nearly 75% (for PET fabrics). For S. aureus the bacterial viability is for this case around values of 45%. Therefore, to state a certain additional antibacterial effect by addition of the effect pigments, the bacterial viability should be significantly below these values measured with the reference systems. The remaining bacterial viability in case of coating with pigment containing recipes is presented in Figure 10. For coatings containing the pigments P1 and P2, no significant decrease in bacterial viability is observed compared to the reference systems. Even though those gold bronze pigments contain copper in a significant amount no additional antibacterial effect is determined, if they are present on the textile fabric. For this it can be stated that these effect pigments do not contain any antibacterial effect going beyond the effect of the pure binder layer. This low activity of those copper pigments can be explained with different arguments. First, copper itself is of weaker antibacterial property compared to other metals as e.g. silver. Second, the used copper pigments are coated to stabilize their surface against oxidation. Third, the release of antimicrobial active copper ion from the surface of alloy pigments is generally low. However for antimicrobial activity it is necessary that copper ions are released from the pigment surface, because the reason for antimicrobial activity is the interaction of bacteria with copper ions. If the copper surface is prevented from oxidation by a coating, obviously less copper ions can be released and the expected biocidal effects, resulting from the released copper ions, should also be smaller. A different antibacterial behavior is observed in case of using the copper/silver-pigment P3. Due to the silver content of this pigment a certain antimicrobial effect is expected and according to this also a significantly decreased bacterial viability is observed (Figure 10). Conclusions Commercially available copper plated fabrics are compared with a set of nine textile samples coated with copper containing effect pigments. The original purposes of such textile materials are • Page 6 of 10 • Citation: Mahltig B, Darko D, Günther K, Haase H (2015) Copper Containing Coatings for Metallized Textile Fabrics. J Fashion Technol Textile Eng 3:1. doi:http://dx.doi.org/10.4172/2329-9568.1000118 Figure 5: Spectra of diffuse reflection and diffuse transmission on the UV/Vis/NIR-range of different metallized fabric types. Figure 6: Spectra of diffuse reflection on the UV/Vis/NIR-range of different coated textiles carrying coatings with different types of metallic effect pigments. Reference spectra are supported for the related uncoated fabrics. Volume 3 • Issue 1 • 1000118 • Page 7 of 10 • Citation: Mahltig B, Darko D, Günther K, Haase H (2015) Copper Containing Coatings for Metallized Textile Fabrics. J Fashion Technol Textile Eng 3:1. doi:http://dx.doi.org/10.4172/2329-9568.1000118 Figure 7: Spectra of diffuse transmission on the UV/Vis/NIR-range of coated cotton and polyester fabrics carrying coatings with different types of metallic effect pigments. Reference spectra are supported for the related uncoated cotton and polyester fabrics. Figure 8: Antibacterial activity of the four investigated metallized polyamide type A to D in comparison to three different uncoated polyamide reference fabrics R1,R2 and R3. The antibacterial properties are determined against the both types of bacteria E.coli and S.aureus. Figure 9: Antibacterial activity of six reference samples without metal component. The references are cotton fabric CO, polyester fabric PET and cotton/polyester blended fabric COPET. These fabrics are investigated as pure fabric or after coating with the pure acrylate binder. The antibacterial properties are determined against the both types of bacteria E.coli and S.aureus. Volume 3 • Issue 1 • 1000118 Figure 10: Antibacterial activity of textile samples with metal pigment containing acrylate coating. The coatings are performed with the pigments P1, P2 and P3 on different types of textiles as cotton fabric CO, polyester fabric PET and cotton/polyester blended fabric COPET. The antibacterial properties are determined against the both types of bacteria E.coli and S.aureus. electric conductivity, EMI-shielding or advanced optical effects. The textile properties according to reflection and transmission of UVand IR-light are reported and indicating a strong influence of the metal on those properties. Advantageous properties could be found here in the fields of radiation protection but also for heat collecting systems. Although the antimicrobial activity of copper containing textiles is reported in the literature, not every one of the currently investigated materials exhibits an antibacterial effect. For some textile surfaces containing copper alloy even no antimicrobial effect can be determined. On the other hand the antimicrobial activity can be significantly enhanced by addition of silver. Therefore, it can be concluded that for commercially available copper containing systems on textile a broad range of antimicrobial activity is possible. Properties as electric conductivity or advanced optical effects are not necessarily combined with antimicrobial properties, if copper containing materials are used for textile functionalization. Altogether it can be concluded, that the application of copper materials onto textile • Page 8 of 10 • Citation: Mahltig B, Darko D, Günther K, Haase H (2015) Copper Containing Coatings for Metallized Textile Fabrics. J Fashion Technol Textile Eng 3:1. doi:http://dx.doi.org/10.4172/2329-9568.1000118 fabrics can lead to advantageous textile materials with many suitable properties, like radiation protection and antimicrobial activity. Acknowledgements 20.Mahltig B, Fiedler D, Simon P (2011) Silver-containing sol-gel coatings on textiles. J Textile Institute 102: 739-745. 21.Mahltig B, Tatlises B, Fahmi A, Haase H (2013) Dendrimer stabilized particles for the antimicrobial finishing of textiles. J Textile Institute 104: 1042-1048. For funding of the electromicroscopic equipment the authors acknowledge very gratefully the program FH-Basis of the German federal country North-RhineWestphalia NRW. For funding of the photospectroscopic equipment the authors acknowledge very gratefully the department of textile and clothing management and the master seminar of the Niederrhein University of Applied Sciences. For support of metallic effect pigments the company Eckart GmbH is gratefully acknowledged and many thanks for helpful and interesting discussions are given to Dr. P. Wissling. All product and company names mentioned in this article may be trademarks of their respective owners, also without labeling. The results presented in the current paper are a part of a broader investigation of effect pigment coatings on textiles performed by Daniel Darko during his master thesis (University of Applied Sciences, Mönchengladbach, Germany, spring 2015). 22.Kelly FM, Johnston JH (2011) Colored and functional silver nanoparticle-wool fiber composites. Appl Mater & Interf 3: 1083-1092. 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Author Affiliations Top FTB, Hochschule Niederrhein – University of Applied Sciences, Faculty of Textile and Clothing Technology, Webschulstr. 31, 41065 Mönchengladbach, Germany 1 Institute of Immunology, Medical Faculty, RWTH Aachen University, Pauwelsstr. 30, 52074 Aachen, Germany 2 Technische Universität Berlin, Institut für Lebensmitteltechnologie und Lebensmittelchemie, Gustav-Meyer Allee 25, 13355 Berlin, Germany 3 Submit your next manuscript and get advantages of SciTechnol submissions 50 Journals 21 Day rapid review process 1000 Editorial team 2 Million readers Publication immediately after acceptance Quality and quick editorial, review processing Submit your next manuscript at ● www.scitechnol.com/submission Volume 3 • Issue 1 • 1000118 • Page 10 of 10 •
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