Masaru Nakajima

Structure and properties of MVS yarns in comparison with ring yarns and open-end rotor spun yarns

The structure and properties of Murata vortex spun yarns are investigated and compared with ring and open-end rotor spun yarns. Cotton yarns are spun from the same lot of Australian raw cotton fibers using the Murata vortex, ring, and open-end rotor spinning methods. Yarn structures are observed with an optical microscope equipped with a digital camera. Based on the digitized photographs, fiber arrangements are classified as wild, wrapper-wild, wrapper, belly-band. and core. Yarn diameter, yarn helix angle, wrapper fiber pitch, wrapper fiber crest, wrapper fiber length for a one-turn twist, and wrapper fiber helix angle to the yarn axis are examined, and yarn parameters such as tenacity, evenness, and hairiness are evaluated. The mechanical properties of dry relaxed yarns are measured with Kawabata Evaluation System instruments. Attempts are made to relate yarn structure differences to differences in the yarn formation mechanism for the three spinning meth ods. The differences in measured yarn properties such as evenness, hairiness, bulkiness. tenacity, compression properties, and bending properties can be explained by the observed differences in the yarn structure.

Effects of Laundering on the Surface Properties and Dimensional Stability of Plain Knitted Fabrics

The effects of laundering and laundering temperatures on surface properties and dimensional stability are investigated for plain flat knit silk, cotton, and polyester fabrics with varying cover factors. The fabrics are subjected to relaxation processes and an extended series of wash and tumble-dry cycles in laundering baths of various tempera tures. Dimensions, surface friction, and roughness of the fabrics are measured in every process. Changes in dimensional stability and surface properties with relaxation processes and laundering temperatures are clarified. Relations between frictional motion and struc tural parameters are also discussed. The results reveal that the dimensional stability of silk is sensitive to a particular temperature. The highest shrinkage is recorded with slackly knitted cotton at the highest temperature. There is a considerable effect of wet relaxation on dimensional stability as well as surface properties. Silks coefficient of friction is the highest, and the lowest surface friction for cotton occurs at the highest temperature. Slackly knitted fabrics also show higher friction than tightly knitted fabrics. The coeffi cient of friction has a tendency to decrease with increasing tightness, while the surface roughness shows an opposite tendency. There is a good correlation between stick-slip motion and ribs on the fabrics.

Dimensional Changes in Knitted Silk and Cotton Fabrics with Laundering

Deformation by laundering is investigated for single jersey and 1 × 1 rib flat knit silk and cotton fabrics with yams of varying linear densities and fabric tightness. The fabrics are subjected to relaxation processes and an extended series of wash and tumble- dry cycles. Changes in dimensions are measured in every process and cycle. Statistical analyses of the experimental data reveal the effect of yam type as well as linear density and tightness factor on the linear and area shrinkage behavior of silk as compared to cotton. Cotton shrinks more than silk, and silk rib knits stretch excessively in width. Silk attains full relaxation after one laundering cycle. Microscopic views reveal the appearance of ball-like formations along silk fibers after repeated laundering. It is possible to predict fabric dimensional changes with wet relaxation as well as with laundering, especially in silk.

Sensory Measurements of the Main Mechanical Parameters of Knitted Fabrics

Mechanical parameters such as bending rigidity, thickness, compressibility, and coef ficient of friction are measured by a sensory method for a series of plain and rib weft knitted structures made from cashmere and polyester textured yarns. The values estimated by the sensory method are found to be in fairly good agreement with the values measured on the KES system. The results of our work indicate that by using a standard and controlling the handling manner, sensory assessments can be as successfully quantified as instrumental measurements. However, detectable differences in each mechanical param eter vary with the sensory assessment, depending on the property being considered. The sensory measurement of fabric thickness yields the most consistent and accurate results. Other parameters such as the bending rigidity, compressibility, and coefficient of friction are also reasonably estimated. In addition, the effectiveness of the sensory measurements is also discussed in terms of knit construction and fiber type.

Effects of Yarn Bending and Fabric Structure on the Bending Properties of Plain and Rib Knitted Fabrics

This work deals with the bending properties of a series of plain and rib weft knitted structures made from cashmere yarns. Additionally, some plain weft knitted fabrics made from polyester textured yarns (PET) are included for comparison. The experimental results are discussed in terms of the structural characteristics (cover factor, fabric weight) and their effects on the bending properties. Theoretical analyses of the effects of yarn bending properties and fabric structure on the bending rigidity and frictional bending moment of the fabrics are based on our straight parallel yarns (SPY) model. In this model, the knitted structure is assumed to consist of a series of straight yarns that have some overlapping regions at the interlocking points. The estimation of fabric bending parameters is based on summing up the bending parameters of these straight yarns, which have some overlapping regions lying in the direction of bending. The estimated values from this model are compared with the values measured on a KES-FB pure bending tester; the predictions are in a reasonable agreement with the experimental data.

Compression of Plain Knitted Fabrics Predicted from Yam Properties and Fabric Geometry

This work proposes a simple theoretical model for plain knitted fabric compression. The work assumes that plain knit compression can be obtained from a combination of piled layer (PL) yarn compression and single layer (SL) yarn compression with a contribution factor depending on the fabric geometry. Experiments involve compression of plain knitted fabrics made from 2/19 and 2/29 tex cotton and 2/43 tex cashmere yams and their compression properties. The relation between compressional energy and cover factor is also investigated. A comparison of the experimental pressure-displacement curves of the fabrics and those calcu lated based on the theoretical model using the experimental compression data of the yarns shows that the model is acceptable for explaining plain knit compression. This model can be considered as a basic step toward improving the knowledge of knitted fabric compression as it relates to yarn compression and fabric geometry.

Using Sodium Bisulfite as a Rinsing Auxillary in Bleaching Cashmere

The effects of rinsing processes using sodium bisulfite, phosphorous acid, acetic acid, and pure water on cashmere bleaching are investigated. Sodium bisulfite, upon bleaching, provides better whiteness than the other agents. It appears that even under mordanting conditions that provide maximum whiteness without causing discoloration visible to the eye, iron deposits on the fibers in ferric form. During rinsing with sodium bisulfite, this iron is removed effectively from the fibers by reducing to ferrous form, as evidenced by the improved whiteness. Under conditions of conventional rinsing, sodium bisulfite damages fibers less than pure water.

Effects of Ferrous Mordanting on Bleaching of Camel Hair

The ferrous mordanting process used for bleaching pigmented fibers has been improved. The serious problems of discoloring and excessive damaging of bleached fibers associated with the deposition of iron during the mordant bleaching process are resolved. All mordanting parameters are critical for successful bleaching of pigmented fibers. When used at a specific temperature and a specific time during mordanting, a reagent (reductive agent or acid) capable of stabilizing the mordant bath (during treatment) produces the most complete reaction of melanin with the iron, while not allowing the iron to be deposited on the keratin. Thus, in the subsequent bleaching process, maximum whiteness is achieved with less damage in terms of the mordanting. Sodium bisulfite can be used as an auxiliary, i.e., at the initial 4.0 pH of the bath, and acetic acid and citric acid can also be applied during mordanting without causing discoloration and excessive damage. The optimum conditions for mordanting are 20°C and 15 minutes when sodium bisulfite is used, and 60°C and 15 minutes with a stabilizer of acetic acid or citric acid. The improved process is, in all respects, superior to conventional processes, with no need for after-treatment with a reducing agent.

Strategic planning for CIM to enhance the competitive ability

Abstract A method of developing strategic CIM is described. Relationship between CIM and firms competitive power is clarified, and a fundamental planning procedure for CIM is developed for enhancing the competitiveness. In the procedure, the system configuration of CIM is analyzed using 0–1 goal programming techniques. A numerical example is also demonstrated to show the effectiveness of the procedure.

The Effects of Bale-opening on the Quality of Intermediates in the Spinning Process

In comparison with conventional models, a finer and more uniform tuft is claimed to have been obtained with a new model of bale opener. Its effects on the quality of intermediates in the carding, combing, drawing, and spinning processes such as carded lap, combed and drawn sliver, and spun yarn are investigated. As a result, homogeneous laps and slivers having small values of the coefficient of variation were obtained, and other favorable results, such as spun yarn having better uniformity and less yarn breakage in the spinning process, were expected.