Forcibly spinning was applied to fully grown larvae of domestic Bombyx mori silkworm and the tensile properties of as-spun fibers were investigated. Tensile strength could be gained by elevating the spinning speed. However, it could not reach the level of naturally spun one. Forcibly spinning may be convenient to produce a finer filament. However, its applicability is limited due to the low spinnability of non-liquid crystalline sericin.
Hair colouring by using dyestuffs formed by the oxidation of (+)-catechin (Cat.) under light irradiation was studied and the oxidation system was combined with photosensitisers which absorb visible light and generate oxidants. Rose bengal (RB) and Methylene Blue (MB) were used as the visible light photosensitiser. Hair was treated with the solutions containing them and was irradiated with artificial sunbeam in dry condition or in Cat. aqueous solution. It was found that hair is not coloured when it is pretreated with the aqueous solutions containing Cat., RB and MB, and irradiated with the light in the dry condition (dry system). In contrast, hair is coloured most when it is pretreated with the solutions containing RB and MB, and then irradiated with the light in Cat. aqueous solution (wet system). The RB and MB in hair may promote the oxidation of Cat. and production of colourants to give better colouration results, when the treated hair is irradiated with visible light in the solution condition.
The hair dyeing using green tea extracts containing high amount of catechins in combination with chemical oxidants such as O2, H2O2 and NaIO4 was attempted in order to establish a novel hair dyeing technique without using aromatic amines contained in commercial oxidation dye products. The new hair dyeing technique consists of a twostep colouration system. The first step is treatment of hair with tea extract solution and the second one is oxidation treatment. Three kinds of oxidation methods such as (1) treating hair with basic dyeing solution (pH = 11.5) supplied with large amount of O2 gas (O2 method), (2) treating hair with H2O2 solution (pH = 9.5) (H2O2 method), (3) treating hair with NaIO4 solution (pH = 7) (NaIO4 method) were attempted as the second oxidation treatment. The results show that once dyed hair is discoloured by H2O2 in the oxidation process and white hair is hardly coloured by the method. In contrast, white hair is dyed brown by the O2 or NaIO4 method, and the dyeability increases with increasing temperature of the first tea extract treatment. This may be due to the increase in the amount of dye precursors adsorbed onto hair by heating. Colour fastness of the hair samples dyed by the O2 and NaIO4 method to washing is almost same level as that by the commercial oxidation dyes. The NaIO4 method is more useful than the O2 method because the supply of O2 gas is unnecessary for the NaIO4 one and it uses the neutral solution.
In order to apply the supercritical fluid dyeing system to cotton fabrics, we investigated the dyeing condition of cotton fabric with reactive disperse dye under supercritical carbon dioxide (scCO2). The reaction condition between hydroxyl groups of cotton and vinylsulfone group of reactive disperse dye was examined by using divinilsulfone as the model of dye. The attractive condition to achieve the high reaction rate between the cotton fabric and the divinylsulfone was treated with 50 mM of ethylene diamine at 120°C and 25 MPa under scCO2. Based on this condition, the dyeing condition of cotton fabric was examined using the synthesized thiazole azo reactive disperse dye having vinylsulfone group. Although it is effective to add a small amount of water up to 3wt% on CO2 to obtain the large dyeing depth of cotton fabric, the color fading occurred in the fabric with long time dyeing and it was therefore necessary to set the dyeing time to 4 h.
Safety quality on the static electrical propensity of work clothes in Japan is confirmed by electrical resistivity or frictional electric charge obtained from the results of test methods specified by International Electrotechnical Commission standard (IEC) or Japanese Industrial Standard (JIS). In practical use, we consider that the hazard related to static electrical charge is dependent on human body voltage caused by various movement of worker during working hours as well as electrical resistance or electric charge amount of work clothes. We thought up two trial movements for determination of human body voltage: one is taking off movement after performing frictional action between work clothes and inner wear during 20 seconds at speed of 90 times per one second, and the other is standing up from the seat of popular use chair quickly after performing frictional action between the back part of work clothes and the back of a chair during 60 seconds at speed of 90 times per one second. Experimental works were performed by using four types of unprotected commercial work clothes and six types of static protected commercial work clothes. As the experimental results, standing up movements from the seat of chair were recorded higher human body voltages than taking off movement. From the almost all work clothes including static protected work clothes, the human body voltage above 3000 voltage which many human felt static electrical shock were detected by the standing up from the chair quickly after performing frictional action.
In this study, we proposed the novel modeling method of stretchable fabrics using lateral strain coefficient. First, a stretchable plain weave fabric and a knitting fabric were focused, and the specification of each stretchable fabric was experimentally verified. We found that a knitting fabric has a lateral strain, but a stretchable plain weave fabric does not has a lateral strain. Next, we proposed a fabric model using lateral strain coefficients, and the calibration method of the lateral strain coefficient was represented. Then, the relationship between deformed shape difference and the lateral strain coefficient is discussed. Finally, comparison example of fabric deformation shape with proposed modeling method is shown. We focused on the situation of a fabric covering a robotic joint. The deformed shapes of each stretchable fabric around a joint were calculated with the proposed modeling method. The comparison results show that, the crinkled shapes of fabrics are different in each fabric.
Flowability of resin and fibers during forming process of short fiber-reinforced plastics was evaluated by Moving Particle Semi-implicit (MPS) particle-simulation. For injection molding of short fiber-reinforced plastics, there are several design parameters. It is inefficient in terms of time and cost to optimize the parameters based on experimental procedures. In this study, a numerical prediction using MPS particle-simulation was applied. In particular, a new analysis method of local flow accompanied by change of time and analysis area was developed to solve discrepancies of the distribution of velocity between global injection area and local flow area. As the numerical results, resin flow and fiber orientation in injection molding had same tendency with global injection molding analysis and the proposed MPS analysis. Therefore, it is concluded that the proposed method contributed to evaluate resin flow and fibers in injection molding process of short fiber-reinforced plastics.
When nanofibers are used for filters, their water resistance is important. We tried to realize the water resistance of nanofibers with ethylene-vinylalcohol copolymer (EVOH) made from aqueous solvent. We also investigated the incorporation of polyurethane (PU) emulsion dispersed in water to improve the adhesion between the nanofibers and the nonwoven fabric of the substrate, and to improve rubber elasticity to the nanofibers themselves. There are few reports on research to produce nanofibers by electrospinning method by combining these two techniques to make the solvent as water as possible. It was possible to realize the nanofiber production of EVOH in a state close to the aqueous system which was difficult up to now by combining with PU. Since PU is excellent in adhesion and firmly adheres to the nonwoven fabric of the base material, peeling of the nanofibers from the base material does not occur, and excellent PM 2.5 particle removal is possible even with very small nanofiber basis weight. Furthermore, it was found that nanofibers can be produced even by using a coil type electrospinning apparatus for industrialization. In the future, to reduce the solution concentration of PU / EVOH to 10 wt%, it is necessary to devise measures such as increasing the hydrophilic component in the structure of PU.
The behavior of heat transfer in various pad as quilting materials is evaluated by analyzing kinetics of layered cloth. In the analysis of heat-transfer kinetics, physical properties of conductivity and transfer are identified by numerical formulations and inverse analysis procedure for the kinetics of quilting materials. Here, the heat transfer kinetics of 3-layer quilting materials are formulated and calculated by assessing the surface temperature of outer cloth. The surface temperature of cloth in wind tunnel is measured from outside of the tunnel by using a digital radiation temperature sensor. The specific thermal resistivity of the quilt pad is analyzed from the measured temperature by evaluating the thermal resistance of layered cloth of 3-layer quilting materials. As a result of this analysis, it is confirmed that silk pad has the heat transfer kinetics value higher than resin pad.