Transaction Textile Performance of Polyester, Nylon 6 and Acetate Fabrics Treated with Atmospheric Pressure Plasma Jet Keiko Gotoh ＊1,#, Akiko Katsuura ＊1,AyaHonma＊1, and Yasuyuki Kobayashi ＊2 ＊1 Faculty of Human Life and Environment, Nara Women’s University, Nara 630-8506, Japan ＊2 Electronic Materials Research Division, Osaka Municipal Technical Research Institute, Osaka 536-8553, Japan Abstract: Three synthetic textiles, polyester, nylon 6 and acetate fabrics, were treated by atmospheric pressure plasma (APP) jet with nitrogen gas. From the contact angle measurements using a single fiber, the wettability and the base parameter of surface free energy of the three fibers were found to increase drastically after the APP treatment. X-ray photoelectron spectroscopy and atomic force microscopy showed that the APP exposure increased the oxygen concentration and the roughness, respectively, for any fiber surface. It was confirmed from the stress-strain behavior and the visible reflection spectrum that the APP impact damage was negligibly small for any fabric. The increase in hydrophilic nature of the fiber surface resulted in promoting water wicking and soil release by laundering. Moreover, the color strength of the polyester and acetate fabrics dyed with disperse dyestuff was found to increase mainly by the topographical change in the fiber surface. Such improvement of textile performances by the APP treatment was remarkable for the polyester fabric. (Received 18 March, 2013 ; Accepted 26 July, 2013) 1. Introduction Recently, we have carried out the surface oxidation of synthetic fibers by two dry processes in the atmosphere. In general, synthetic textiles have many advantages Some synthetic textiles were treated by 172 nm ultraviolet of high modulus and strength, stiffness, stretch, wrinkle (UV) excimer light irradiation [21]. As a result, the water and abrasion resistances, relatively low cost, convenient absorbency for any fabric was enhanced because of the processability, tailorable performance and easy recycling increase in single fiber wettability. Such a tendency was [1, 2]. On the other hand, they have low wettability remarkable for polyester, which surface oxygen because of inherently hydrophobicity, which leads to less concentration and roughness much increased due to UV wearing comfort, low color strength, build-up of exposure compared with other synthetic fibers. The color electrostatic charge, the tendency to pilling and strength after dyeing and the detergency by laundering insufficient washability [2, 3]. Because of these were also improved after UV irradiation for the polyester disadvantages, surface modification to enhance fabric [22]. Moreover, we have applied atmospheric hydrophilicity has been carried out by conventional pressure plasma (APP) to polyester textile finishing. The chemical modifications [4-7]. The chemical modification APP jet device used has attracted significant attention, can improve textile-specific performance by altering its because they generate plasma plumes in open space, have chemical structure due to a chemical reaction, such as no limitations on the sizes of the objects to be treated and esterification, grafting, and crosslinking. Therefore, large can achieve continuous in-line material processing at high amounts of modifying agents and solvents are required, speed [23-27]. To obtain basic information on resulting in undesired high-cost drying and pollutant- physicochemical properties of the treated surface, the treating steps [4, 7]. As alternative environmentally PET film with geometric simplicity was chosen [28, 29]. friendly technology, dry gas-phase oxidation of synthetic The increases in wettability and surface free energy were fiber surfaces after processing has been recently remarkable for the APP treatment in comparison with the attempted by ultraviolet light [8-13] and plasma [7, 14- UV treatment, which was not in contradiction with the 20] technologies. results characterized by X-ray photoelectron spectroscopy. Using polyester fabric, it was confirmed that the APP jet # corresponding author treatment increased oxygen concentration and roughness （47） SEN’I GAKKAISHI（報文）Vol.69, No. 9 (2013) 169 of the fiber surface [30] and successfully enhanced the The water was purified (resistivity of 18 MΩcm) water wicking, the detergency and the color strength of using a Direct-Q UV apparatus (Millipore, USA). the fabric [31]. Moreover, it was found that the changes in 2.2 APP and UV exposure polyester fiber surface properties and fabric performances The APP exposure was performed using a plasma due to the APP exposure were dependent on the reactive pretreatment equipment (Plasmatreat GmbH, Germany) gas source used. [30, 31]. consisting of a plasma generator (FG1001), a high- In the present paper, polyester, nylon 6 and acetate voltage transformer (HTR1001) and a rotating nozzle jet filament fabrics were exposed to the APP with nitrogen (RD1004). The APP was generated by means of a high- gas, which was the most effective for the polyester voltage discharge inside the nozzle jet coupled to the surface modification. The optimum processing parameter stepped high-frequency pulse current power supply was determined from the balance between the fiber (plasma generator) [32]. The operating voltage, current wettability increase and the fabric damage. The fabric and frequency are 285±5V, 6.0±0.1A and 16±3 kHz, performances such as water wicking, detergency by respectively. The reactive gas used was nitrogen, which laundering and color strength after dyeing were evaluated was regulated the pressure and the flow rate to be from the viewpoint of multi-functionalized textiles. The 0.3 MPa and 20 l/min, respectively. The plasma nozzle jet changes in fiber surface characteristics and fabric of 40 mm in diameter was set vertically and a piece of performances were compared among the fabrics. fabric was horizontally placed from the nozzle at a separation distance of 3-7 mm. During the exposure, the 2. Experimental fabric was moved in the horizontal direction at 0.16 m/sec 2.1 Materials (exposure time : 0.25 s), which were chosen as the Three plain-woven fabrics composed of filament uniformly treatable velocity with references to the yarns were used for the experiment. Polyester and nylon 6 experimental results in the previous papers [28]. Both fabrics (JIS Test Fabric) were purchased from Japanese sides of the polyester fabric were exposed to the APP. Standard Association, and acetate fabric from Shikisensha To compare with the APP treatment, the fabrics were Co., Ltd, Japan. The fabrics were purified in boiled water exposed to UV excimer light using a UV excimer lamp at twice prior to use. a wavelength of 172 nm in ambient air using a Xe2 Water, diiodomethane, ethylene glycol and n- excimer vacuum UV apparatus (UER20-172, Ushio, pentane were used for the contact angle measurement. Japan). The intensity of the UV excimer light at the upper As model soils, we used carbon black (SEAST SP, SiO2 glass window of the lamp house, on which the fabric Tokai Carbon Co. Ltd., Japan) and oleic acid. Sudan Ⅲ was placed, was determined to be 15.8 mW/cm2 using an (oily-soluble dye, CI 26100, Wako Pure Chemical UV monitor system (UIT-150 and VUV-S172, Ushio). Industries, Ltd., Japan)was chosen as a tracer of oleic acid. Both sides of the fabric were exposed to UV for 60 s [33]. Sodium dodecyl sulfate (SDS, Wako Pure Chemical 2.3 Evaluation of contact angle and surface free Industries, Ltd., Japan) and sodium chloride were used for energy preparation of the detergent solution. The advancing and receding contact angles of water Disperse dyes for polyester, Sumikaron Yellow SE- on the fiber surface were determined by the wetting force 4G and Sumikaron Brilliant Violet SE-BL (Sumika measurement employing the Wilhelmy method [30, 34]. Chemtex Co., Ltd, Japan), acid dyes for nylon, Kiwacid G. A single fiber of 10 mm in length, which was taken from Yellow 4RL-N and Kiwacid Blue GL-N (Kiwa Chemtex the warp yarn of the fabric, was suspended from the arm Co., Ltd, Japan), and disperse dyes for acetate, Kiwalon of the electrobalance (Model C-2000, Cahn Instruments Polyester Yellow DR and Kiwalon Polyester Blue DR-G Inc., USA). Just below the fiber, a glass vessel containing 150 (Kiwa Chemical Industry Co., Ltd. Japan), were used. water was placed on the stage connected to a stepping As dispersing agents, Smipon SE (Sumika Chemtex Co., motor (MP-20L, MICOS, Germany). A continuous Ltd, Japan), Newbon TS-400 and Nicca Sansalt 1200K weight recording was made during an immersion- (Nicca Chemical Co., Ltd, Japan) were chosen. The pH of withdrawal cycle at an interfacial moving velocity of dye bath was adjusted with acetic acid and sodium acetate. 0.3 mm/min [35]. As after-treatment agents, Laccol ISF-2 (Meisei Chemical The weight recording for a treated single fiber Works, Ltd, Japan), Sunlife E-37 (Nicca Chemical Co., showed periodic variation along the fiber axis, indicating Ltd, Japan), sodium hydroxide and sodium hydrosulfate that the fiber surfaces were not treated uniformly because were used. of fiber crimps due to the structure of the fibrous 170 SEN’I GAKKAISHI（報文）Vol.69, No. 9 (2013) （48） assembly [30]. Therefore, the minimum advancing and 2.6 Evaluation of water wicking receding contact angles were obtained from the advancing The wicking rate, the movement of water in the and receding wetting forces, respectively, using the capillaries of a fabric, was evaluated by two methods on Wilhelmy equation. referring to JIS L1907 [40]. The contact angles of diiodomethane and ethylene A water drop was placed on the fabric (50 × 50 mm2) glycol were also measured for the estimation of the and photographs were taken at given times until 60 sec. surface free energy of the fiber. The Lifshitz-van der The spreading area on the fabric was determined by Waals and the Lewis acid-base and components were binary processing using 2D image analysis software calculated from the advancing contact angles of water, (WinRoof Ver.