Warm/Cool Feeling Characteristics of Ceramic-Incorporated Fabrics: Process, Characterization, and Thermal Properties

Abstract

Recently, high-performance functional textile goods have been commercialized using various ceramic nanopowders, such as ZrC, Al₂O₃, SiO₂, ZnO, ATO, and TiO_2, embedded in the yarns and fabrics. This study examines the warm-cool feeling characteristics of ceramic-incorporated fabrics with their process, characterization, and thermal characteristics. This topic is divided as follows: review (introduction), preparation (experimental), characterization with thermal property (results and discussion), and summary. As a review, heat release and storage properties of the various ceramic-embedded fabrics are introduced and multifunctional properties of different ceramic-embedded fabrics such as UV-cut and anti-static with thermal wear comfort are reviewed with types of ceramic particles embedded in the yarns through the literature published up to now. In the text, warm-cool feelings of ceramic-embedded fabrics prepared in this study are compared in terms of heat flow rate (Qmax) and thermal insulation value (TIV) and summarized with dye-affinity and color-fastness of the ceramic-embedded fabrics. Finally, the future prospect for functional to textiles treated with ceramic materials is proposed in the fields of water repellence, anti-bacteria, flame retardation, anti-static, and UV protection.

1. Introduction

Heat storage and retention warm-up textile materials have been used in sportswear and lingerie with eco-friendly and environmentally functional textile materials. Many commercialized warm-up textile materials were developed by Japanese companies, such as Unitica [1], Kuraray [2], Mitsubishi-rayon [3], Toray [4], and KB seiren [5]. Many studies and technical reports for this area have been provided despite the confidentiality related to technical information by the manufacturing company [6, 7, 8, 9]. Improving heat storage and retention of the warm-up textile materials in the company mainly involves three types of technology: micro-multilayer fiber with high hollowness [10, 11], heat release/storage by ceramic-embedded technology, and heat development using a phase change material (PCM) [12, 13, 14]. Of these technologies, ceramic-embedded technology has attracted considerable attention because of its appearance in the market by many Japanese textile companies.

On the other hand, many studies [15, 16, 17, 18, 19] related to their interactions between the heat released from the ceramic particles in the yarns and infrared radiation have been carried out using a range of ceramic particles, such as ZrC, Al₂O₃, and SiO₂. Negishi and Kikuchi [15] reported the heat-absorbing property of ZrC particles and that they reflected far-infrared (FIR) radiation. Furuta et al. [16] examined the heat storage and moisture permeability of the ZrC-embedded PET fabric. Bahng and Lee [17] reported the heat-generating and rapid moisture absorption/drying properties of the Al₂O₃-embedded fabrics. Anderson et al. [18, 19] reported increased solar absorption with an increased TiO₂ content embedded in the PET filament and presented the thermal outwear made from TiO₂-embedded fabric designed for cold-weather applications. Kim and Kim [20, 21] examined the thermal properties and wear comfort of the ZrC-embedded PET fabrics.

On the other hand, some studies [22, 23, 24, 25] related to thermal and wear comfort were performed using regular and special fibers with a change in the yarn and fabric structural parameters. Matsudaira [22] examined the moisture and heat transmission of the eight types of fabric specimens made from different grooved hollow fibers. They reported that the thermal conductivity of the fabric specimens differed according to the cross-sectional shape of the grooved hollow fibers, and the maximum heat flow (Qmax) of the fabric specimens was primarily affected by the contacted surface area between the fibers in the yarn. Furthermore, the thermal insulation value (TIV) of the fabric specimens was strongly dependent on the cross-sectional shape of the grooved hollow fibers. Onofrei et al. [23] examined the influence of knitted fabrics structure on the thermal and moisture properties using Coolmax® and Outlast®. They reported the importance of a knitted fabric structure suitable for summer and winter sportswear by analyzing their heat and moisture characteristics. Supuren et al. [24] examined warm-cool characteristics through the moisture management and thermal absorptivity of double-face knitted fabrics used in sports/activewear using a cotton/polypropylene (PP) blend yarns. Majumdar et al. [25] examined the thermal properties in terms of thermal conductivity, wet thermal resistance, and air permeability of knitted fabrics made from cotton and regenerated bamboo cellulosic fibers. They reported the thermal wear comfort according to the knitted fabric structure and pattern. In addition to these studies, several studies have measured the warm-cool feeling characteristics [26, 27, 28] and clothing temperature change using a phase change material [29, 30, 31]. However, few studies have examined the thermal wear comfort with the dyeability and color fastness of Nylon/PP sea and island warm-up knitted fabrics incorporated with fine ceramic powders.

On the other hand, high functional fibers have become applicable to intelligent textile materials, where self-regulating control of cold and hot weather is possible by the release and absorption of heat [6, 12]. Among them, cool textile materials used in hot weather are made from phase change materials (PCM) [6, 13, 14] and moisture-responded transformable (MRT) fiber [14, 32], which are called intelligent textiles or smart textiles. Recently, Mather [33] proposed that PCM, shape memory polymers (SMPs), and breathable fabrics, including thermochromism and photochromism, could apply to intelligent textiles. The MRT fiber was developed by Teijin in Japan, which has been commercialized to knitted fabrics for sportswear [32]. MRT fibers are expanded after moisture absorption like the hygral expansion (HE) of wool fibers. Kim and Kim [32] examined the physical properties of Huvis elastic fiber (HEF) developed by Huvis Co. Ltd. in Korea, which is similar to the MRT fiber of Teijin in Japan. Many studies [24, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43] focused on improving the coolness feeling characteristics of sweating have been carried out using fabric manufacturing technology by combining hydrophobic and hydrophilic yarns. Of these studies, D. Mikucioniene et al. [34] examined heat transfer characteristics of the water absorption and fast-drying knitted fabrics made from cotton/synthetic composite yarns. M. Piraee et al. [35] reported the thermal characteristics of 13 acrylic knitted fabrics with different stitch length. M. Yanilmaz [36] investigated wear comfort with absorption and drying properties of acrylic knitted fabrics with different structures. Chen et al. [38, 39, 40] reported the extent of the coolness of nylon and PET knitted fabrics using initial absorption rate and wicking rate measured from biomimetics of branching structure. Fan et al. [41] and Sarkar et al. [42, 43] conducted intensive studies to improve the moisture absorption of multilayered fabric on plant-based fabric structures.

On the other hand, commercially applied coolness textile technologies include two types of technology: one is perspiration absorption and fast-dry fiber material with a noncircular cross-sectional shape, Coolmax®, as a well-known brand of Dupont (Invista). In particular, perspiration absorption and fast-drying properties (coolness characteristics) of fabrics using Coolmax® and Outlast® have been examined by some textile scientists [23, 44, 45, 46, 47]. Onofrei et al. [23] examined the influence of knitted fabric structure on the thermal and moisture properties of knitted fabrics using Coolmax®. Kim and Kim [44, 45, 46, 47] examined the wicking and drying properties as coolness characteristics and heat retention rate as warmness characteristics of woven fabrics made from PET and PP composite yarns with Coolmax®/bamboo/Tencel fibers. They reported that the Coolmax®/Tencel sheath/core fabrics exhibited superior wicking and drying properties applicable to coolness fabrics for summer outdoor clothing.

Another technology uses ceramic-incorporated hydrophilic PET fiber material with superior heat transfer properties using ethylene vinyl alcohol (EVOH) as a hydrophilic heat transfer material, which was commercialized in Japanese companies, such as Kuraray and Komatsu-seiren. Sophista®, made in Kuraray is manufactured using composite spinning technology with three types of yarn cross-sections: sheath/core, multilayer, and multi-hollow with hydrophilic heat transfer material, EVOH, which enables a cool feel to the wearer while it contacts the human skin. Aqusia® made in Komatsu-seiren was commercialized using bicomponent spinning with nylon with ceramic powders and hydrophilic PET. It is composed of a sheath filled with ceramic-incorporated nylon and a core with hydrophilic and high heat transfer PET. On the other hand, despite the many fiber manufacturing companies providing considerable technical information as a commercial base, various physical properties, including the coolness feel of the hydrophilic and heat transfer PET, are less known for confidentiality reasons. Recently, Huvis Co. Ltd. in Korea developed a ceramic-embedded hydrophilic PET coolness filament with noncircular and different shaped cross-sections, but there are no reports of the detailed coolness feeling and dyeability data according to the dyeing processing factors in terms of the dyeing temperature and time.

Therefore, this study examined warm/cool feeling characteristics of ceramic incorporated fabrics, and which is composed of two part, first part examined the thermal wear comfort in terms of maximum heat flow (Qmax) and thermal insulation value (TIV) of the warm-up knitted fabric specimens made from Nylon/PP sea and island composite filaments incorporated with fine ceramic particles. Second part examined the physical properties of the ceramic-embedded hydrophilic PET coolness filament developed by Huvis Ltd. Co. in Korea. The coolness feeling of the knitted fabric made from the ceramic-embedded coolness filament was compared with that of control knitted fabrics made from hydrophobic PET coolness and regular PET filaments. In particular, the effect of ceramic powders incorporated in the coolness filament to the cool feeling was examined. In addition, the dye-affinity, color difference, and color fastness to the washing of hydrophilic PET coolness fabrics with noncircular and different shaped yarn cross-sections were compared with dyeing process factors, such as different dyeing temperatures and times, and discussed with those of the control fabrics, such as hydrophobic PET coolness and regular PET fabrics.

2. Literature review on application of ceramics to textiles goods

Improving the warm feel of textiles mainly involves three types of technology: heat of wetting by water absorption, heat release using phase change material (PCM), and heat storage/release by ceramic-incorporated technology. On the other hand, cool feel technologies of textiles are classified into four types: perspiration absorption and fast-drying PET with a noncircular cross-sectional shape (Coolmax®) and nylon high hollow fiber (Wincall®) using conjugated spinning, hydrophilic PET fiber with superior heat transfer property using ethylene vinyl alcohol (EVOH) by bicomponent (sheath/core) spinning, PCM material, and moisture-responded transformable (MRT) fiber technologies. Of these technologies, hydrophilic PET fiber with EVOH using a bicomponent spinning is composed of a sheath filled with ceramic powder and a core with hydrophilic and EVOH PET polymer. As mentioned above, ceramic powders are applied to both warm and cool-feeling textiles.

Therefore, many studies related to warm/cool feeling textiles have been explored using ceramic powders with many researches to improve UV protection, anti-static, and anti-bacteria properties. Recently, high-performance functional textile goods have been commercialized using various ceramic nanopowders, such as ZrC, Al₂O₃, SiO₂, ZnO, ATO, and TiO₂, embedded in the yarns and fabrics. Among several methods treated with ceramic powders to the textiles, coating is a common technique used to apply nanopowders onto textiles, however, the coating has some issue in washing durability according to the repeated washing and laundering of the treated textiles. In recent, a new method by novel scheme, not a conventional one such as coating method was developed. Accordingly, recent studies related to heat release and storage by thermal radiation, including UV protection and anti-static properties, using various ceramic particles are critically reviewed in this literature survey. In early years, scientific studies [15, 16, 17, 18, 19] related to their interactions between heat released from various ceramic particles embedded in the yarns and infrared radiation were conducted using various ceramic particles, such as ZrC [15, 16], Al₂O₃, SiO₂ [17], and TiO₂ [18, 19]. More recently, Kim and Kim [20, 21, 48, 49, 50] conducted an intensive study on the heat release/storage and thermal wear comfort of ZrC/Al₂O₃-embedded PET fabrics. They [20, 21] examined FIR emission characteristics of ZrC-embedded knitted fabrics and reported the thermal wear comfort of the ZrC-embedded fabrics via thermal manikin experiment. They concluded that ZrC absorbs the heat emitted from the human body or reflects the FIR radiation, which prevents the heat in the clothing and human body from flowing out.

In addition, Kim and Kim [21] examined heat release/storage properties and thermal wear comfort of Al₂O₃/graphite and ZrC/graphite-embedded fabrics. They reported that the heat release characteristics of the ZrC/graphite-embedded fabrics were superior to those of the Al₂O₃/graphite-embedded fabrics. In addition, various wear comfort properties of the fabrics using thermal manikin and wearer trials with human subjects were examined and reported that the wear comfort properties of the ZrC/graphite-embedded fabric were superior to those of the Al₂O₃/graphite-embedded fabric. In further studies, Kim [48] examined the thermal radiation and wear comfort properties of the Al₂O₃/graphite-embedded fabrics according to the embedded yarn structure distributed by ceramic particles in the yarns. Moisture absorption and drying properties using a moisture management tester (MMT) and thermal insulation property by a KES-F7 system were measured and compared with two ceramic-embedded yarn structures (sheath/core and dispersed yarn). In particular, Kim [49, 50] examined the dry and wet thermal wear comfort properties of the Al₂O₃/graphite-embedded fabrics for cold weather protective clothing according to ceramic particles distributed yarn structures using a sweating thermal manikin apparatus [49]. Thermal insulation (Clo value) using a thermal manikin of the Al₂O₃/graphite-embedded fabrics was compared with thermal radiation (FIR emissivity and maximum surface temperature) in terms of yarn structure such as sheath/core, dispersed, and regular PET yarns [50].

On the other hand, many studies [51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62] using various ceramic particles to improve UV protection and anti-static characteristics of the fabrics have been conducted with fabrics coated with different ceramic powders. Of these studies, some studies [51, 52] examined the increase of the effectiveness of UV protection by coating treatment of TiO₂ and others [53, 54, 55] reported more efficient UV protection of ZnO-coated fabric than conventional one. TiO₂ and ZnO among various ceramic particles were used as UV blockers, which were more efficient at absorbing and scattering UV radiation than the other ceramic particles. In contrast, ATO (antimony tin oxide) and ZnO particles provide an anti-static property with electrically conductive characteristics [56, 57, 58, 59, 60, 61, 62], which helps to effectively dissipate the static charge accumulated on the fabrics coated with ZnO [59, 62] and ATO nanopowders [56, 57, 58, 60, 61]. In particular, ATO particles have a thermal insulation property with a heat shielding effect [58]. However, most of the previous studies given by the coating treatment have limitation to the durability of the function during wearing clothing and laundering. Hence, functional yarns and fabrics produced from new scheme, not coating have been required.

Most recently, Kim [63, 64] reported UV protection and anti-static characteristics of the ATO/TiO₂/Al₂O₃-embedded PET fabrics produced from new scheme, that is, bicomponent spinning method, and showed the applicability of these yarns to workwear protective clothing because of their superior UV protection and anti-static characteristics. By the way, the hazard posed by static electricity is heightened considerably in cold and dry environments in cold weather regions, particularly, oil and gas industries are located, where the workwear protective clothing requires superior thermal wear comfort with the anti-static property. In addition, apart from dramatically reducing exposure to the sun to the workman exposed to sunlight, the most frequently recommended form of UV protection is the use of UV protective clothing. Accordingly, workwear protective clothing wearing in winter and cold weather regions requires multifunctional high performance such as anti-static and UV cut with superior thermal wear comfort.

In recent, Kim [65, 66] examined the UV protection and anti-static properties with thermal radiation of the Al₂O₃/ZnO/ZrC/ATO-embedded fabrics to investigate their properties according to the mixing of ceramic particles embedded in the yarns. They reported that ZnO/ZrC and ZnO/ATO-embedded fabric exhibited superior UV protection due to excellent UV protection characteristics of the ZnO ceramic particles. ATO-embedded fabric showed superior anti-static properties with lower rub-static voltage and surface electrical resistivity (SER). Based on multifunctional high-performance protective fabric, it was found that ZnO/ATO-embedded fabric is of practical use for engineering workwear protective clothing with superior UV protection factor (UPF), excellent anti-static property, and relatively good thermal radiation. In addition, ZnO/ZrC-embedded fabric was expected to be applicable to workwear protective clothing wearing in cold weather regions because of excellent thermal radiation, UPF, and relatively good anti-static property.

3. Experimental

3.1 Specimen preparation

3.1.1 Yarn specimens

The Nylon/PP composite filament was spun as sea and island-type partially oriented yarns (POY) on the conjugated spinning machine installed in Huvis Co. Ltd. (Suwon, Korea). Ceramic nanopowders (ZrC, 0.6 wt.%) were embedded in the core part with PP polymer on the bicomponent spinning machine. Ceramic-incorporated Nylon/PP warm-up POY was texturized on a texturing machine (AIKI, Japan), which was used as a warm-up yarn specimen (W-1) to make a warm-up knitted fabric specimen. In addition, two types of ceramic-incorporated PET (W-2 and 3) and one regular PET (W-4) yarn were used as the control yarns to make the knitted fabric specimens, which were compared with the ceramic-incorporated nylon/PP warm-up knitted fabric.

On the other hand, the yarn specimen used as a coolness yarn was developed and spun on a pilot spinning machine in Huvis Co. Ltd. (Suwon, Korea). The developed yarn specimen (C-1) was a hydrophilic ceramic-embedded (TiO₂, 0.3 wt.%) PET coolness filament with noncircular and different-shaped cross-sections. One control yarn specimen (C-2) was a hydrophobic PET coolness filament, and the other control yarn specimen (C-3) was a regular PET filament. The hydrophilic PET polymer was first polymerized to impart hydrophilicity by adding intermittently polyol molecules between the molecular chains of terephthalic acid (TPA) and ethylene glycol (EG). A noncircular and different-shaped cross-section was imparted in the spinning process. The ceramic nanopowder was incorporated into this process to give a coolness feel. Table 1 lists the specification of the yarn specimens.

Specimens	Specification	Characteristics	Remark
W-1	Nylon/PP 75^d/36^f	Sea/island composite yarn	Developed
W-2	PET 75^d/72^f	Nano-ceramic-incorporated PET	control
W-3	PET 75^d/72^f	Ceramic-incorporated PET	control
W-4	PET 75^d/72^f	Regular PET	control
C-1	PET 75^d/36^f	Hydrophilic PET coolness yarn	Developed
C-2	PET 75^d/72^f	Hydrophobic PET coolness yarn	control
C-3	PET 75^d/72^f	Regular PET yarn	control

Table 1.

Characteristics of the yarn specimens.

3.1.2 Knitted fabric specimens

Warm-up knitted fabric specimens were fabricated using four types of yarn specimens on a circular knitting machine (Double knitting m/c, Geumyoung, Daegu, Korea). The specifications of the knitting machine for warm-up knitted fabrics were as follows: 30-inch diameter, 18 gauge, 2640 stitch, and 18 rpm speed, and 28 gauge for coolness fabric specimens, was used with 15 rpm speed. The pattern of the warm-up knitted fabric specimens was a double jersey with the loop side used by four types of yarn specimens (Table 1) and the float (back) side with covering yarn composed of 150d/96f PET DTY and spandex 20d.

The pattern of the coolness knitted fabric specimens was also double knit. Table 2 lists the patterns of the warm-up and coolness knitted fabric specimens.

Warm-up knitted fabric specimen		Characteristics (Design)
Pattern (double knit & fancy structure)	Cam sequence
	Yarn sequence		a		b	c	d		e	f
	Dial	B	⋃		⋁	—	—		V	—
		A	—		⋁	—	⋃		⋁	—
	Cylinder	A	—		—	⋀	⋂		—	⋀
		B			—	⋀	—		—	⋀
	Stitch sequence
	Dial	A			B		A			B
	Cylinder	A			B		A			B
Coolness knitted fabric specimens		Characteristics (Design)
Pattern (double knit & interlock single pique structure)	Cam sequence
	Yarn sequence			a	b	c	d	e	f	g	h
		Dial	B	⋃	⋁	⋃	⋁	—	⋁	—	⋁
			A	—	⋁	—	⋁	⋃	⋁	⋃	⋁
		Cylinder	A	⋀	—	⋀	—	⋀	—	⋀	—
			B	⋀	—	⋀	—	⋀	—	⋀	—
	Stitch sequence	Dial	A	B	A	B	A	B	A	B
		Cylinder	A	B	A	B	A	B	A	B

Table 2.

Pattern and design of the knitted fabrics.

Yarn: a, b, d, e: surface yarn; sequence c, f: PET 150d/96f SD: DTY + Spandex 20d. note: ∪, ∩: tuck; ∧, ∨: knit; —: miss. note: ∪: tuck; ∨, ∧: knit; —: miss.

3.1.3 Dyeing and finishing treatments of the knitted specimens

The Nylon/PP knitted fabric specimen (W-1) was scoured with Na₂CO₃, 2 g/ℓ and Sunmorl S-30, 1 g/ℓ at 80°C for 20 minutes in a CPB scouring machine. After scouring, the knitted fabric specimens were dyed with 3% o.w.f. of C.I. acid blue 288 with newborn, 1 g/ℓ, acetic acid PH-4 in a rapid machine. The PET knitted fabric specimens (W-2, −3, and − 4) were dyed with C.I. disperse blue 78 with RM 340, 0.5 g/ℓ, and washed with NaOH, 2 g/ℓ and Na₂S₂O₄, 1 g/ℓ at 80°C for 20 minutes in a CPB scouring machine. The dyeing conditions of the warm-up knitted fabric specimens were shown in Table 3. The process conditions for coolness knitted fabrics were provided in Table 3. The optimal dyeing conditions were determined by changing the dyeing time and temperature for the nylon/PP warm-up and coolness PET knitted fabric specimens. Table 3 lists the dyeing conditions of the knitted fabric specimens.

Specimens	Dyeing condition		Temp.increment	M/C
	Temp (°C)	Time (min)
W-1	80,90,100	30,40,60	3 °C/min	IR; dyeing m/c
W-2	110,120,130	30,40,60
W-3	110,120,130	30,40,60
W-4	110,120,130	30,40,60
C-1	110,120,130	30,40,60	Scouring Soda ash(Na2CO3)2 g/l,; Scouring agent(Sunmorl SS-30) 1 g/l, 80°C, 20 min; Dyeing Disperse dye (FORONBLUES–BGL 200–Claiant),(C.I. Disperse Blue 78); dispersing agent(RM340)0.5 g/l; Weight reduction NaOH 2 g/l, Na2S2O4 1 g/l, 80°C, 20 min
C-2	110,120,130	30,40,60
C-3	110,120,130	30,40,60

Table 3.

Dyeing conditions of the knitted fabric specimens.

3.2 Measurement of yarn physical properties

The tenacity and breaking strain of the yarn specimens were measured according to KSK 0416 with a gauge length of 100mm and a crosshead speed of 100mm/min using Testomeric Micro 350 (USA); 20 readings were taken for each specimen. The dry and wet thermal shrinkages were measured using the KSK 0215 measuring method. Cross-sections of the yarn specimens were assessed to determine the ceramic particles incorporated in the yarns using scanning electron microscopy (SEM, S-4300, Hitachi Co., Japan).

3.3 Measurement of the thermal properties of the knitted fabric specimens

The thermal wear comfort of the warm-up knitted fabric specimens was measured using a KES-F7 (Thermolabo II, Kato Tech. Co. LTD., Japan) measuring apparatus [67]. The maximum heat flow at the transient state (Qmax, J/cm²·s) of the knitted fabric specimens were measured using a KES-F7 system at 20 ± 1°C and 70 ± 5% RH. A 10 cm x 10 cm specimen was prepared and assessed using Eq. (1). An average of five readings for each specimen was reported.

$${\mathrm{Q}}_{\max }=\left[\mathrm{ʃq}\left(\mathrm{t}\right)\mathrm{dt}\right]=\frac{\mathbf{M}\mathbf{·}\mathbf{C}}{\mathbf{A}}\frac{\mathbf{dT}\left(\mathbf{t}\right)}{\mathbf{dt}}\mathbf{dt}$$E1

where q(t) is the heat absorption rate per unit area of the specimen (cal/sec·cm²); A is the area of the plate; M is the mass of the heat plate; C is the specific heat of heat plate (cal/g·°C); and dT(t)/dt is the heat decreasing rate of the heat plate.

Thermal insulation value (TIV) of the knitted fabric specimens was measured as a measure of the heat insulation rate using Eq. (2) [67].

$$\mathrm{TIV}=\left(\mathbf{1}-\frac{\mathbf{b}}{\mathbf{a}}\right)\times \mathbf{100}$$E2

where a is the heat loss (W) of the plate without a specimen, and b is the heat loss (W) of the plate covered with a specimen.

3.4 Measurement of the dye affinity and color fastness of the knitted fabric specimens

The dye affinity characteristics of the knitted fabric specimens were examined at different dyeing temperatures and times. Reflectance (R) of the knitted fabric specimens according to the dyeing temperature and time was measured using a color measuring device (Gretag Macbath, Color-Eye 3100, USA). The dye affinity (K/S) was calculated from R using Eq. (3) [68].

$$\mathrm{K}/\mathrm{S}={\left(1-\mathrm{R}\right)}^2/\text{2R}$$E3

where R, K, and S are the reflectance, absorption factor, and scattering factor, respectively.

In addition, the color difference (ΔE) was measured, and the color fastness to washing of the knitted fabric specimens was assessed according to the KS K ISO 105-C06.

4. Results and discussion

4.1 Physical properties of warm-up yarn specimens

The weavability of the yarns is very important for estimating fabric productivity, which can be estimated and compared by the tenacity and breaking strain of yarn. Table 4 lists the tenacity and breaking strain of the warm-up yarn specimens.

Specimen	Tenacity (g/d)		Breaking strain (%)		Thermal shrinkage (%)
	Mean	Dev.	Mean	Dev.	Mean(D)	Dev. (D)	Mean(W)	Dev. (W)
W-1	4.086	0.223	4.515	2.534	18.6	3.8	18.8	2.6
W-2	4.661	0.328	1.672	1.853	18.2	1.7	16.7	6.9
W-3	4.056	0.303	0.600	0.811	14.7	4.7	13.6	4.3
W-4	4.721	0.481	1.563	2.015	14.5	2.3	14.3	7.7

Table 4.

Physical properties of warm-up yarn specimens.

Note: dev. = max. – min. D: dry, W: wet.

As shown in Table 4, the tenacity of the warm-up yarn specimens ranged from 4 to 5 gf/d, which is estimated as the free value of weavability in the weaving process. In addition, the tenacity of nylon/PP filament (W-1) was slightly lower (4 gf/d) than that of the other yarn specimens (W-2, −3, and − 4). Furthermore, W-1, −2, and − 3 exhibited lower tenacity than the regular PET yarn (W-4). This suggests that sea/island yarn and nano-ceramic-incorporated yarn deteriorated yarn tenacity because of the boundary characteristics of the two components between the base polymer in sea/island yarn and nanoparticles incorporated in the yarns. Figure 1 presents SEM images of the cross-section of yarn specimens, W-1, −2, and − 3. The sea/island yarn cross-section in Figure 1a and nanoparticles of ceramics in Figure 1a–c are shown as white spots.

Figure 1.

SEM images of a cross-section of the ceramic particle-incorporated yarns. (a) W-1, (b) W-2, (c) W-3.

As shown in Table 4, the breaking strain of the Nylon/PP yarn (W-1) was much higher (4.5%) than that of the other three yarn specimens because of the difference between the nylon and PET yarn characteristics. As shown in Figures 2, 36 filaments in yarn specimen 1 were shown, and 72 filaments in yarn specimens 2, 3, and 4 were appeared, respectively. In particular, the breaking strain of yarn specimen 3 showed the lowest value, which was attributed to the larger ceramic particles incorporated in yarn specimen 3 than the other yarn specimens. Figure 1c shows that the ceramic particles in yarn specimen 3 are larger than that of yarn specimens 1 and 2 (Figure 1a, b), and these particles enable the yarn subjected to stress to be inextensible, resulting in a lower breaking strain.

Figure 2.

SEM images of the cross-sections of the yarn specimens (x1000). (a) W-1, (b) W-2, (c) W-3, (d) W-4.

Estimating the thermal shrinkage of the newly developed yarns is essential for designing relevant dry and wet thermal shrinkages of fabric in the dyeing and finishing processes. Therefore, in this study, the thermal shrinkages of newly developed nylon/PP warm-up composite yarn were compared with the other three yarn specimens. Table 4 lists the dry and wet thermal shrinkages of the yarn specimens. The dry and wet thermal shrinkages of the nylon/PP warm-up composite yarn (W-1) ranged from 18 to 19%, which were higher than those of specimens 3 and 4, respectively, which was attributed to the higher dry and wet thermal shrinkages of the nylon and PP than those of PET. In addition, the dry and wet thermal shrinkages of the nylon/PP warm-up composite yarn (W-1) and nano-ceramic particle-incorporated PET yarn (W-2) exhibited a similar value. This suggested that nano-ceramic particles incorporated in the yarns imparted thermal stability to the dry and wet thermal deformation.

4.2 Thermal wear comfort of the warm-up knitted fabric specimens

4.2.1 Contact-warm feeling

The Qmax (maximum heat flux) was defined as a measure of the warm/cool feeling by contacting fabric measured using the KES-F7 apparatus. Figure 3 shows the mean of Qmax of the warm-up knitted fabric specimens according to dyeing temperature and time.

Figure 3.

Qmax of the warm-up knitted fabric specimens.

The Qmax at the transient state of the nylon/PP knitted fabric (W-1) was lower than that of the ceramic-incorporated and regular PET knitted fabrics (W-2, −3, and − 4). This was attributed to the greater heat emitted from the ceramic particles incorporated in the core of the nylon/PP composite yarns, which prevented heat flow from the human body to outside through the fabric, resulting in a lower Qmax of the nylon/PP knitted fabric specimen even though the thermal conductivity of the nylon is higher than that of the PET. This result was partly due to the lower thermal conductivity of ceramic-incorporated PP than TiO₂-incorporated PET [69], which resulted in a lower Qmax of the nylon/PP knitted fabric (W-1) than the ceramic-incorporated PET fabrics (W-2, −3, and − 4).

4.2.2 Thermal insulation value (TIV) of the warm-up knitted fabric specimens

Understanding how the ceramic-incorporated characteristics of nylon/PP sea and island composite yarns affect the TIV of the nylon/PP warm-up knitted fabric is essential to evaluating the thermal wear comfort for winter clothing. Figure 4 presents a diagram of the TIV of the warm-up knitted fabric specimens. The TIV of the nylon/PP warm-up knitted fabric (W-1) was higher than that of the other knitted fabrics (W-2, −3, and − 4), which was attributed to the greater heat emanating from the ceramic particles incorporated in the islands of the nylon/PP sea and island composite yarn than PET yarns and lower thermal conductivity of the PP in the core of the composite yarns than PET yarns, which prohibited heat flow from human skin to the outside through the knitted fabric, resulting in a higher TIV of the nylon/PP warm-up knitted fabrics than the ceramic-incorporated and regular PET fabrics.

Figure 4.

TIV of the warm-up knitted fabric specimens.

The TIV of the nylon/PP warm-up knitted fabric (W-1) was approximately 9.3% higher than that of the ceramic-incorporated PET knitted fabrics (W-2 and -3), highlighting the importance of the ceramic particles embedded in the sea and island yarn structure with a low thermal conductivity of PP incorporated in the island to the TIV of the fabrics.

4.3 Dyeability and color fastness of warm-up knitted fabric

4.3.1 Dye affinity characteristics

The dyeing characteristics of the nylon/PP ceramic-incorporated fabric were compared with those of the ceramic-incorporated PET and regular PET fabrics according to the dyeing temperature and time. Figure 5 presents the dye affinities (K/S) of the warm-up knitted fabric specimens. The K/S of the nylon/PP knitted fabric (W-1) was lower than that of the ceramic-incorporated PET and regular PET fabrics (W-2, −3, and − 4). This was attributed to the low dye affinity of the PP fibers in the island of the nylon/PP sea and island composite yarns compared to PET and nylon. In addition, the changes in the dye affinity according to the dyeing temperature and time appeared differently between the nylon/PP and three PET fabrics.

Figure 5.

K/S of the warm-up knitted fabrics according to dyeing condition.

In the case of nylon/PP ceramic-incorporated fabric (W-1), the K/S decreased with increasing dyeing temperature and increased with increasing dyeing time at dyeing temperatures of 80 and 100°C, but it decreased at a dyeing temperature of 90°C. The ceramic-incorporated and regular PET fabrics (W-2, −3, and − 4) showed a different trend of K/S according to the dyeing temperature and time. The dye affinity of the ceramic-incorporated PET fabrics W-2 and -3 according to the dyeing temperature and time was slightly higher than that of the regular PET fabric (W-4). Furthermore, the dye affinity of the ceramic-incorporated PET fabrics (W-2 and -3) at a dyeing temperature of 110°C decreased with increasing dyeing time. At a dyeing temperature of 120°C, the dye affinity increased with increasing dyeing time. At 130°C, the dye affinity decreased and increased with increasing dyeing time. The optimal dyeing conditions in the dyeing process of the nylon/PP sea and island warm-up knitted fabric were a dyeing temperature of 80°C and a 40 min dyeing time. The optimal conditions for the ceramic-incorporated PET knitted fabrics were 110°C and 30 min, at which K/S showed the highest value.

4.3.2 Color fastness to washing of the warm-up knitted fabric specimens

Table 5 lists the color fastness to washing of the warm-up knitted fabric specimens according to the dyeing temperature and time. The color fastness to washing of the nylon/PP knitted fabric was superior to that of the ceramic-incorporated and regular PET fabrics, which was superior in the staining fabric, such as acetate and nylon, than cotton, polyester, acrylic, and wool. In particular, the color fastness to washing of the ceramic-incorporated PET-knitted fabrics exhibited a superior grade (4–5) to staining fabrics such as cotton, acrylic, and wool regardless of the dyeing temperature and time.

Staining fabric		Acetate				Cotton				Nylon				Polyester				Acrylic				Wool
Dyeing temp. (°C)	Dyeing time (min)	W-1	W-2	W-3	W-4	W-1	W-2	W-3	W-4	W-1	W-2	W-3	W-4	W-1	W-2	W-3	W-4	W-1	W-2	W-3	W-4	W-1	W-2	W-3	W-4
80, (110)	30	4–5	3	3	3	4–5	4–5	4–5	4	4–5	2–3	2–3	2–3	4–5	3–4	3–4	4	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5
	40	4	3–4	3	4–5	4	4–5	4–5	4–5	4	3–4	2–3	4	4–5	4	3–4	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5
	60	4	3–4	3–4	3–4	4–5	4–5	4–5	4–5	3–4	3–4	3	3	3–4	4	4	4	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5
90,; (120)	30	4–5	3–4	3–4	3–4	4–4	4–5	4–5	4–5	4–5	3	3	3–4	4–5	4	4	4	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5
	40	4–5	4	3–4	4–5	4–5	4–5	4–5	4–5	4–5	4	3	4	4–5	4–5	4	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5
	60	4–5	4	3–4	4–5	4–5	4–5	4–5	4–5	4–5	4	3	4	4–5	4–5	4	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5
100,; (130)	30	4–5	4	4	4–5	4–5	4–5	4–5	4–5	4–5	4	3–4	3–4	4–5	4–5	4	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5
	40	4–5	4–5	3–4	4	4–5	4–5	4–5	4–5	4–5	3–4	3	3–4	4–5	4–5	4	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5
	60	4–5	4–5	4	4–5	4–5	4–5	4–5	4–5	4–5	4	3–4	4	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5

Table 5.

Color fastness to washing of the warm-up knitted fabric specimens.

Note: 80, 90, 100 °C for W-1; 110, 120, 130°C for W-2, 3 and 4.

4.4 Physical properties of the cool feeling yarns

According to Huvis Co. Ltd. [30], hydrophilic PET coolness yarn with noncircular and different shaped cross-sections of the constituent filaments in the yarn was spun on the melt spinning machine using a ceramic nanopowder mixed polymer made by adding an intermittently polyol molecule between the molecule chains of TPA and EG. Therefore, the tensile properties of the hydrophilic PET coolness yarn were examined and compared with those of the hydrophobic PET coolness and regular PET yarns. Figure 6 presents SEM images of cross-sections of the three coolness yarn specimens.

Figure 6.

SEM images of cross-sections of three kinds of coolness yarn specimens. C-1, C-2, (c) C-3.

The noncircular and different shaped cross-sections of the constituent filaments in the hydrophilic (C-1) and hydrophobic (C-2) coolness PET yarns were observed. Ceramic nanoparticles in the hydrophilic coolness PET yarn were noted, which were larger than those of the hydrophobic coolness PET yarns. The SEM image of a circular cross-section of each filament in the regular PET yarn (C-3) was slightly distorted because of the false twist in the texturing process. Table 6 lists the physical properties of the three coolness yarn specimens. The tenacity of the hydrophilic (C-1) and hydrophobic coolness (C-2) PET yarns was lower than that of the regular PET yarn (C-3). This was attributed to the ceramic particles in the yarn. Hence, the boundary characteristics between the base polymer and ceramic particles incorporated in the yarns deteriorated the tenacity of the yarns. The breaking strain of the hydrophilic coolness PET yarn (C-1) was compared with those of the hydrophobic coolness (C-2) and regular PET (C-3) yarns, and was lower than that of C-2 and -3, which was attributed to a similar reason to tenacity.

Specimen	Tenacity (g/d)		Breaking strain (%)		Thermal shrinkage (%)
	Mean	Dev.	Mean	Dev.	Mean (D)	Dev. (D)	Mean (W)	Dev. (W)
C-1	4.182	0.758	3.371	0.741	13.280	0.623	6.674	1.186
C-2	4.542	0.634	5.350	0.528	16.418	2.895	15.214	3.648
C-3	4.886	0.326	5.640	0.289	9.562	1.945	4.348	0.675

Table 6.

Physical property of coolness yarn specimens.

Note: D: dry; W: wet.

The wet and dry thermal shrinkages of the yarns need to be considered to examine the process design for the wet and dry heats subjected to the dyeing and finishing processes. The wet and dry thermal shrinkages of the three coolness yarn specimens were listed in Table 6. As shown in Table 6, the wet and dry thermal shrinkages of the hydrophilic and hydrophobic coolness PET yarns (C-1 and -2) were higher than those of the regular PET (C-3) yarns, respectively. This was attributed to the higher thermal conductivity of the ceramic nanoparticle-incorporated PET yarns than that of the regular PET yarn, which gave these yarns higher thermal stress, resulting in higher thermal shrinkage. In addition, the wet and dry thermal shrinkages of the hydrophilic coolness PET yarn (C-1) were lower than those of the hydrophobic coolness PET yarn (C-2), respectively. This was attributed to the formation of a hydrogen bond between the molecular chain formed by the moisture in the hydrophilic coolness PET yarn, which enabled the hydrophilic yarn to deform less from the internal thermal stress caused by the wet and dry heats, resulting in lower wet and dry thermal shrinkages than the hydrophobic yarn. In addition, which was partly attributed to the larger ceramic particles embedded in the C-1 yarn, as shown in Figure 6, than those in the C-2 yarn, which makes less thermal shrinkages.

4.5 Contact cool feeling characteristics of the coolness knitted fabrics

Qmax measures the contact cool feeling as human skin contacts the fabric in the transient state. Figure 7 shows the mean of Qmax of the three coolness knitted fabric specimens according to the dyeing temperature and time.

Figure 7.

Mean Qmax of the coolness knitted fabrics.

The Qmax of the hydrophilic (C-1) and hydrophobic coolness (C-2) PET fabrics was higher than that of the regular PET knitted fabric (C-3). This was attributed to the higher thermal conductivity of the ceramic particles in the yarns, which provided higher heat transfer, resulting in a higher Qmax of these knitted fabrics than the regular PET fabric. On the other hand, the Qmax of the hydrophilic coolness PET fabric (C-1) was slightly lower than that of the hydrophobic coolness PET fabric (C-2), which was attributed to hydrogen bonding between the molecular chains in the hydrophilic PET yarn (C-1), and partly attributed to the larger ceramic particles embedded in the hydrophilic coolness yarns (C-1) than those in the hydrophobic coolness yarn (C-2). Hence, they prevent heat emanating from the human body from flowing to the outside through the fabric, resulting in a lower Qmax of the hydrophilic coolness PET fabric than the hydrophobic fabric.

Figure 8 presents the Qmax of the three coolness knitted fabrics according to dyeing temperature and time. A considerable change in the Qmax of the hydrophilic (C-1) and hydrophobic coolness PET (C-2) fabrics according to the dyeing temperature and time was not observed. On the other hand, the Qmax of the three fabric specimens treated with 110°C dyeing temperature (30 and 40 min) was slightly higher than those treated with 120°C and 130°C (30 and 40 min), which means the better coolness feeling of fabrics treated with a 110°C dyeing temperature. Particularly, in the hydrophilic coolness fabric (C-1), the highest Qmax was observed at a dyeing temperature of 110°Cand dyeing time of 30 or 40 min. Hence, a superior coolness feeling was achieved using these dyeing conditions.

Figure 8.

Qmax of the coolness and regular PET knitted fabrics.

4.6 Dye-affinity and color fastness characteristics of the coolness knitted fabric specimens

The dye-affinity characteristics of the three knitted fabrics were compared and discussed according to the dyeing temperature and time. Figure 9 presents the dye-affinity (K/S) of the three knitted fabrics according to the dyeing temperature and time. As shown in Figure 9, the K/S of the hydrophilic coolness PET knitted fabric (C-1) was higher than those of the hydrophobic coolness and regular PET knitted fabrics (C-2 and C-3), which was attributed to the higher dissolution speed of the disperse dyestuff due to the hydrophilic property of the C-1 yarn specimen compared to the C-2 and C-3 yarn specimens.

Figure 9.

K/S of the coolness knitted fabric specimens.

Furthermore, the dye-affinity of the C-1 was accelerated by increasing the diffusion speed into the hydrophilic structure in the yarn. In addition, the K/S of the C-1 showed the highest value at the dyeing temperature, 110°C regardless of the dyeing time, and decreased slightly with increasing dyeing temperature, indicating that the hydrophilic coolness PET knitted fabric (C-1) shows high dye-affinity efficiency at the low dyeing temperature. Figure 10 presents the ΔE of the three knitted fabric specimens according to the dyeing temperature and time. The ΔE of the C-1 was higher than those of the C-2 and C-3 like K/S. This was attributed to a similar reason explained in the K/S. The ΔE of the C-1 and C-2 decreased with increasing dyeing temperature and exhibited the highest values at a dyeing temperature of 110°C, demonstrating high dye-affinity efficiency at the low dyeing temperature of the ceramic-incorporated PET knitted fabrics.

Figure 10.

ΔE of the coolness knitted fabric specimens.

Table 7 lists the color fastness to washing of the three knitted fabrics treated with different stain fabrics according to the dyeing temperature and time. The color fastness to washing of the C-1 and C-2 was slightly inferior to C-3 against stain fabrics such as acetate and nylon. The color fastness to washing of the C-1 specimen showed superior values (grade: 4 or 5) and was similar to those of C-2 and C-3 against the stain fabrics, such as cotton, polyester, acrylic, and wool, regardless of the dyeing temperature and time.

		Acetate			Cotton			Nylon			Polyester			Acrylic			Wool
Dyeing temp.; (°C)	Dyeing time (min)	C-1; PET	C-2; PET	C-3; PET	C-1; PET	C-2; PET	C-3; PET	C-1; PET	C-2; PET	C-3; PET	C-1; PET	C-2; PET	C-3; PET	C-1; PET	C-2; PET	C-3; PET	C-1; PET	C-2; PET	C-3; PET
110	30	3–4	3–4	4–5	4–5	4–5	4–5	3	3	4	4	4	4–5	4–5	4–5	4–5	4–5	4–5	4–5
	40	4–5	4–5	4–5	4–5	4–5	4–5	4	4	4	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5
	60	4–5	4–5	4–5	4–5	4–5	4–5	3–4	4–5	3–4	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5
120	30	4–5	4–5	4	4–5	4–5	4–5	4	3–4	3–4	4–5	4	4	4–5	4–5	4–5	4–5	4–5	4–5
	40	4–5	4–5	4–5	4–5	4–5	4–5	4	4	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5
	60	4–5	4–5	4–5	4–5	4–5	4–5	4	4	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5
130	30	4–5	4–5	4–5	4–5	4–5	4–5	4	3–4	4	4–5	4	4–5	4–5	4–5	4–5	4–5	4–5	4–5
	40	4–5	4–5	4–5	4–5	4–5	4–5	4	4	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5
	60	4–5	4–5	4–5	4–5	4–5	4–5	4	4	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5	4–5

Table 7.

Color fastness to washing of the coolness fabric specimens.

5. Summary

The thermal wear comfort of the warm-up knitted fabric made from the ceramic-incorporated nylon/PP sea and island filament was examined, and the dye-affinity of the nylon/PP-knitted fabric was also investigated according to the dyeing temperature and time. The tenacity and breaking strain of the nylon/PP composite yarn were approximately 4gf/d and 4.5%, respectively, meaning that there was no problem in weavability in the weaving process. The dry and wet thermal shrinkages of the nylon/PP composite yarns ranged from 18 to 19%, which were higher than those of the regular PET yarns. The Qmax of the nylon/PP warm-up knitted fabric was lower than that of the regular PET knitted fabric, which was attributed to the greater heat emitted from the ceramic particles incorporated in the core of the nylon/PP composite yarns. In addition, the TIV of the nylon/PP knitted fabric was approximately 9.3% higher than that of the regular PET knitted fabric, which was also attributed to the greater heat emanating from the ceramic particles incorporated in the island of the nylon/PP sea and island yarn than PET yarn. Considering energy savings in the dyeing process, the optimal dyeing condition from the K/S dye-affinity result of the nylon/PP ceramic-incorporated knitted fabric was a dyeing temperature of 80°C and a dyeing time of 40 min. For the ceramic-incorporated PET knitted fabrics, the optimal dyeing condition was 110°C and 30 min. The color fastness to washing of the nylon/PP knitted fabric was superior to that of the ceramic-incorporated and regular PET fabrics for all types of staining fabrics, which was superior for staining fabrics, such as acetate and nylon, than cotton, PET, acrylic, and wool.

On the other hand, the contact coolness feeling (Qmax) and dyeability characteristics of the ceramic incorporated and hydrophilic coolness feeling PET knitted fabric were examined in terms of the dyeing temperature and time. The tenacity and breaking strain of the ceramic incorporated hydrophilic coolness PET yarn were approximately 4.18 g/d and 3.4%, respectively, which was estimated as being no problem in weavability in the weaving process. The dry and wet thermal shrinkages of the hydrophilic coolness PET yarn were 13.3 and 6.7%, respectively, which was 1.3 to 1.5 times higher than those of the regular PET yarn. The Qmax of the ceramic incorporated hydrophilic and hydrophobic coolness PET knitted fabrics were higher than that of the regular PET fabric, indicating the superior contact coolness feeling of these fabrics. The maximum value of Qmax of the hydrophilic coolness PET knitted fabric according to the dyeing temperature and time appeared at a dyeing temperature of 110°C and dyeing time of 30 or 40 min, that is, exhibited superior contact coolness feeling at this dyeing condition. Considering the energy saving and dyeability of the newly developed yarn and fabric in the dyeing process, the K/S of the ceramic-embedded hydrophilic coolness PET knitted fabric decreased with increasing dyeing temperature, irrespective of the dyeing time, and higher than those of the hydrophobic coolness and regular PET fabrics. In addition, the maximum K/S value of the ceramic-embedded hydrophilic coolness PET fabric according to the dyeing temperature and time was observed at 110°C and 30 min or 40 min, indicating the optimal dyeing conditions for high dye-affinity and low energy consumption. The ΔE of these fabric specimens according to dyeing temperature and time showed a similar trend to the K/S. The color fastness to washing of the ceramic-embedded hydrophilic coolness knitted fabric was slightly inferior to the regular PET fabric in the case of stain fabrics such as acetate and nylon, whereas it was superior in the case of stain fabrics, such as cotton, polyester, acrylic, and wool, regardless of the dyeing temperature and time.

6. Concluding remarks

Application areas of ceramic particles to textiles are known as water repellence, anti-bacteria, flame retardation, anti-static, and UV protection. Concerning water repellence, nano-tex improved the water-repellent property by creating nano-whiskers of hydrocarbons, which are added to the fabric to create a peach fuzz effect [58]. The performance is permanent while maintaining breathability, and a hydrophobic property can be imparted on the fabrics by coating it with a thin nanoparticulate plasma film [70, 71]. For imparting anti-bacterial properties, titanium dioxide (TiO₂) [72, 73, 74] and zinc oxide [53] are used. Fabrics treated with nano-TiO₂ could provide effective protection against bacteria and the discoloration of stains. Nano-ZnO provides effective photocatalytic properties like TiO₂, once it is illuminated by light, imparting anti-bacterial properties to textiles [75, 76, 77]. Flame-retardant (FR) properties of textiles have been explored using special flame-retardant fibers such as modacrylic (Kanekalon, SNIA), fire-retardant viscose rayon (FR-rayon), and anti-static PET fiber, Beltron, has been used in protective clothing for FR and anti-static textile materials [78, 79, 80]. On the other hand, many attempts to obtain flame retardant activity by the formation of a layer of ceramics (glass, SiO₂, Al₂O₃) have been explored [81, 82, 83, 84]. As mentioned previously, abundant research works [56, 57, 61, 62, 63, 64, 65, 66] concerning the improvement of the anti-static properties of textiles were conducted using ceramic particles such as ZnO [62, 65, 66] and ATO [56, 57, 61, 63, 64, 65, 66]. In addition, ceramic UV blockers are usually certain semiconductor oxides such as TiO₂, ZnO, SiO₂, and Al₂O₃. Of these, TiO₂ [52, 63, 64, 66] and ZnO [53, 54, 55, 65, 66] are commonly used as previously explained. In particular, nano-sized TiO₂ and ZnO are more efficient at absorbing and scattering UV radiation, and several studies on their application of UV protection to fabric were conducted [51, 52, 53, 54, 55, 63, 64, 65, 66]. The application of various ceramic materials to textiles has been highlighted in many papers, and new technology to overcome the limitation of conventional methods will be of practical use for engineering various workwear protective clothings, including fashioned textile materials.