The Effect of Urea on Wool Fibres

The role of urea in the cold dyeing of wool fabrics by commercially feasible methods which use dye liquors containing high concentrations of urea was examined. Urea was found to penetrate wool fibres readily and promote swelling particularly in the presence of sodium bisulphite.     

A Method for Determining the Distribution of Cationic Shrink-resist Resins on Wool*

A method for determining the distribution of cationic shrink-resist resins on wool has been developed. The method is based on a staining technique, using an anionic fluorescent brightening agent (FBA) under specific conditions in which the FBA stains the cationic resin in preference to the wool. When the stained samples are observed under ultraviolet radiation by means of the optical microscope, the areas on the wool fibres where resin is located fluoresce, whereas areas free from resin appear dark. The technique is simple and rapid, and enables the regularity of deposition of cationic resins on wool to be followed when the various parameters which play a role in the pretreatment of the fibre and the application of resins are changed. Regularity of resin deposition is important in the achievement of high levels of shrink-resistance in treated fabrics.     

Protection of Wool Products from Insect Damage by Blending Untreated and Insectproofed Wool

Berber-style products, containing significant amounts of undyed wool, have been found to be protected from insect attack when the untreated wool is blended with wool treated with sufficient insectproofing agent to give 1. 5 times the recommended application level, based on the total wool content. Best protection is obtained if the untreated and treated wool fibres are intimately blended. Adequate protection, in some instances, can be obtained by treating individual yarns. In this case the spatial distribution of the treated wool and untreated wool in the final product is important.     

Reaction of Wool with Alkylamines Possible Technique for Producing Differential–dyeing Wool

The action of methylamine, dimethylamine and trimethylamine on wool has been followed by estimating the amounts of βN–monomethyl–β–aminoalanine (I), βN–dimethyl–β–aminoalanine (II), lysinoalanine and lanthionine formed as a result of the degradation of the cystine residues in the fibre by the amines. Because of the electronegativity of the nitrogen atoms in I and II, the treated fibres are more reactive than untreated ones. The dye substantivity of the treated fibres is much greater than that of the untreated fibres, leading to the possibility of a technique for producing differential–dyeing wool.     

微波处理羊毛的染色性能研究

通过扫描电镜和激光拉曼光谱等技术研究了预处理前后羊毛纤维表面形态结构和二硫键含量的变化。讨论了微波辐射功率和时间对羊毛织物回潮率的影响。采用微波对羊毛进行辐射处理,通过研究微波辐射功率和辐射时间对羊毛染色织物表观得色量的影响优化出了处理羊毛的最佳工艺条件。通过最佳处理条件对羊毛织物进行处理,并且采用毛用兰纳素活性染料和派拉丁1∶1金属络合染料对羊毛织物进行染色,通过上染速率曲线测试了处理前后羊毛的上染性能。对比分析了羊毛织物未经微波预处理和经微波预处理染色后的上染率、固着率和总固着率等染色性能。     

Polysiloxane Softener Coatings on Plasma‐Treated Wool: Study of the Surface Interactions

Low temperature plasma (LTP) improves the shrink‐resistance of wool fabrics but impairs their softness, so different polysiloxane coatings were applied. Modifications in surface hydrophilicity and topography of fabrics and fibres have been recorded through drop test, contact angle and SEM, respectively. LTP improves the deposition of the polysiloxanes which, depending on their functionalities alter the original hydrophilicity of the wool surface. Softness and shrink‐resist results of the fabrics point out to a possible relationship between hydrophilicity of the wool fibre surface and the shrinkage behaviour of the fabrics. A possible mechanism of interaction between the different polysiloxane groups and the surface of untreated (UT) and LTP‐treated wool is proposed.

     

牡丹花天然植物染料对羊毛织物染色性能的研究

将黄色牡丹花天然植物染料用于羊毛织物的染色,探讨了媒染剂和染色方法对羊毛织物染色效果的影响,通过单因素试验和正交试验筛选出以明矾为媒染剂时牡丹花黄色染料对羊毛织物的最佳染色工艺条件,得到了色泽鲜艳的黄色羊毛织物.     

Pretreatment of wool/polyester blended fabrics to enhance titanium dioxide nanoparticle adsorption and self‐cleaning properties

This research aims to enhance the self‐cleaning properties of fibre‐blended fabric using surface pretreatment prior to the application of titanium dioxide nanoparticles. To this end, the polyester/wool fabric was modified, in that the wool fibres were oxidised with potassium permanganate and the polyester fibres were hydrolysed with lipase before nano processing. Butane tetracarboxylic acid was also used to enhance the adsorption of the nanoparticles and also to stabilise them on the fabric surface. The self‐cleaning properties of the fabric were examined through staining of the fabric with CI Basic Blue 9 and then discolouring by exposing to ultraviolet and daylight irradiation. Some other properties of the treated fabrics, such as water drop absorption, crease recovery angle and bending were investigated and are discussed in detail. The colour changes of different samples indicated an appropriate discoloration on the titanium dioxide‐treated fabrics after ultraviolet and daylight irradiation. Overall, the surface pretreatment of the wool and polyester fibres improved the self‐cleaning properties of the fabric significantly.     

Improving the dyeability of wool by treatment with chitosan

A study of pretreatment of wool fabrics with chitosan by a pad-dry method has been carried out. The pretreatment effectively eliminates differences in dyeing behaviour between damaged and undamaged wool fibres, with an increase in the rate of dye uptake and the exhaustion of acid and reactive dyes. Penetration of the fibre by dyes has been followed using fluorescence microscopy and the role of the chitosan coating in the dyeing process clarified. Similar colour fastness properties were obtained on both untreated and chitosan-treated wool fabrics. The chitosan coating on wool fabrics has been examined by scanning electron microscopy. Evidence for the presence of chitosan was sought using a colorimetric method. It is believed that an approximately uniform and adherent chitosan sheath is formed on individual wool fibres.     

壳聚糖在活性染料染羊毛织物上的应用工艺探讨

本文对壳聚糖处理过的羊毛织物用活性蓝BET染色工艺进行了探讨.讨论了壳聚糖脱乙酰度、壳聚糖浓度对羊毛染色性能的影响,并比较了经壳聚糖处理与未处理羊毛染色性能的差异.结果表明,提高处理液中壳聚糖的浓度或脱乙酰度都能提高活性染料的固色率,提高织物表面色深值K/S,而且对染色样的各项牢度影响不大.     

Photoreactivity of Wool Dyed with Reactive Dyes

Presented at the 13th Congress of the International Federation of Associations of Textile Chemists and Colourists in London on 20 September 1984. Processes induced by two kinds of illumination (ultra-violet and Xenotest) in wool dyed with reactive dyes ha ve been investigated as a function of time. The fading of dyed fibres has been determined in terms of the conditions of illumination. The degradation of wool was followed on the basis of changes in alkali solubility and tensile characteristics. Moreo ver the colour change of the dyed fibres was also determined. Correlation was found between the chemical structure of the dye, the extent of fading and the photodegradation undergone by the wool. On the basis of amino acid analysis conclusions were drawn on the photodegradation mechanism of wool, both uncoloured and dyed with reactive dyes. Reactive dyes protect wool against photodegradation, and at the same time the light fastness of reactive dyes on wool is 1–1.5 units higher than on cotton, both under ultra-violet (u.v.) and Xenotest irradiation.     

Development of Environmentally Friendly Wool Shrink-Proof Finishing Technology Based on L-Cysteine/Protease Treatment Solution System

The particular scale structure and mechanical properties of wool fiber make its associated fabrics prone to felting, seriously affecting the service life of wool products. Although the existing Chlorine–Hercosett treatment has a remarkable effect, it can lead to environmental pollution. Therefore, it is of great significance to develop an environmentally friendly and effective shrink-proof finishing technology. For this study, L-cysteine was mixed with protease to form a treatment solution system for shrink-proof finishing of wool fibers. The reduction performance of L-cysteine and its effect on wool were compared with those of other reagents, demonstrating that L-cysteine has an obvious reduction and destruction effect on the wool scale layer. Based on this, L-cysteine and protease 16L were mixed in a certain proportion to prepare an L-cysteine/protease treatment solution system (L/PTSS). The shrink-proof finishing of a wool top was carried out by the continuous multiple-padding method, and the processing parameters were optimized using the response surface method. The results indicated that when the concentrations of L-cysteine and protease 16L were 9 g/L and 1 g/L, respectively, the wool was padded five times at 50 °C, and each immersion time was 30 s, the felt ball density of the treated wool reduced from 135.86 kg/m³ to 48.65 kg/m³. The structure and properties of the treated wool were also characterized using SEM, TG, and tensile strength tests, which indicated that the fiber scale structure was stripped evenly. Meanwhile, the treated fibers still retained adequate thermal and mechanical properties, indicating suitable application value. XPS, FT-IR, Raman, UV absorbance, and other test results revealed the reaction mechanism of L/PTSS with the wool fibers. After L-cysteine rapidly reduced the disulfide bonds in wool, protease can hydrolyze peptide chains more effectively, causing the scale layer to gradually peel off. Compared with the chlorination method and other protease shrink-proof technologies, L/PTSS can achieve the finishing effect on wool rapidly and effectively, without causing excessive pollution to the environment. The conclusions of this study provide a foundation for the development and industrial application of biological enzyme shrink-proof finishing technology.     

Wool Dyeing—A Path to Progress

Recent advances in the dyeing technology of man-made and cellulosic fibres have far outstripped those for wool. The reasons for this are discussed, and possible developments are described on the basis of achievements in other fields of textile dyeing. The present position is analysed from the viewpoint of dyeing techniques and in terms of the dyes and auxiliary products available. Current difficulties in producing dress fabrics to meet fashion demands for bright fast colours are used to illustrate the points raised, and possible methods of surmounting this immediate problem are examined. Special attention is given to the possibilities offered by continuous dyeing procedures for wool, and existing methods are critically surveyed. An attempt is made to define the operating limits of common wool-dyeing machinery, and thereby to underline the areas where re-equipment is needed if instrument-control and automation techniques are to be utilised fully.     

Studies of Urea-assisted Wool Dyeing

Cut segments of wool, as well as whole fibres, have been immersed, under standard conditions, in concentrated aqueous urea. The diameter of each fibre or segment was then determined and compared with that of a control. No swelling occurred with whole fibres, but swelling was observed with the segments, the extent of swelling, in a given time, being inversely proportional to the length of the cut segment. The swelling of cut fibres increased with the time of immersion in concentrated aqueous urea. It is concluded that urea diffused into the cut ends of wool fibres, but that the epicuticle, if intact, is impervious to urea.     

Wool – A Colour–difference Analysis of Fastness–test Data

The possibility of replacing visual assessments of the colour change of dyed wool fabrics subjected to a standard washing test with instrumentally measured colour differences is examined. Washing tests on a wide range of dyeings on Superwash wool were carried out, and the colour difference AE between the washed and unwashed patterns was calculated in AN40 units. The results were compared with routine visual assessments of three observers. Good agreement on ‘pass-fail’ decisions was found between the instrumental and the visual techniques. The ‘pass-fail’ limit of 3–4 on the ISO Grey Scale for Assessing Change in Colour in the Superwash test corresponded to 2. 2 AN40 units over the colour range investigated.     

废旧毛涤黏混纺面料脱色预处理工艺研究

以废旧毛涤黏混纺面料为研究对象,首先对面料进行清洁与消毒,然后对其组分进行定性、定量分析,最后通过单因素法优化,得出最佳的溶胀工艺为:m_(废旧面料)∶m_(DMSO)=1∶10,溶胀时间40 min,溶胀温度90℃。在该工艺下对织物进行溶胀处理,得到织物的质量损失率为3.06%,K/S值为16.906。     

“In Situ” Enzymatically Prepared Polymers for Wool Coloration

Phenolic compounds such as hydroquinone, catechol and ferulic acid can polymerise and therefore develop deep colours when treated with peroxidase and laccase enzymes. We have attempted to apply this phenomenon for wool dyeing. Wool was padded with phenolic compounds and deep colours were developed by enzymatic treatment in buffer solutions. Mordant with chromium compounds or heating under the condition of acid catalysis was available for fixation of these coloured compounds on the wool fibres.     

Stability to Aftertreatments of Wool Set in Thioglycollic Acid

The set obtained on single wool fibres by treatment with thioglycollic acid has been shown to be unstable under normal soaping conditions. The effect of detergents on this set has been examined. Conclusions are drawn about the relative importance of disulphide crosslinks, hydrogen bonds and hydrophobic crosslinks in stabilising the set.     

Photoacoustic Spectroscopy for the Study of the Adsorption of Dyes on Wool Fabrics

Dyes have been applied to different wool fabrics and measurements by photoacoustic spectroscopy showed well-defined absorption bands. Differences were found in the spectral properties of dyes, which appeared visually to be very similar, indicating that photoacoustic spectroscopy may be useful for the identification of dyes on wool fabrics. Photoacoustic spectroscopy was also shown to be capable of measuring two-dye and three-dye combinations and very dark colours. Comparisons with reflectance spectroscopy showed that photoacoustic spectroscopy might usefully complement the results obtained from reflectance measurements.     

Dyeing of Blends of Wool and Man-made Fibres

The blending of wool with man-made fibres is described generally. It is shown how the results of dyeing wool-man-made-fibre blends are controlled by physical properties such as wet tensile modulus; it is also indicated how a wide range of coloured effects can be obtained with different man-made fibres. The dyeing of blends containing wool is considered first from the point of view of the circulation of dye liquor through a mass of fibre and then of the relative dye absorption by the blend components. The relationship between tensile modulus and behaviour in wet processing is illustrated by laboratory work on the measurement of rate of flow through a mass of loose fibre. It is concluded that the dyeing of loose fibres in blend form could be a practical proposition and in some cases could result in over-all economies in processing. The relative dye absorption by fibres in blends is discussed in detail and fibres are classified according to their substantivity for acid or for direct dyes. One group consists of regenerated-protein, polyamide, and elastomeric fibres, a second group of viscose rayon fibres, and a third, larger, group of hydrophobic fibres, e.g. acetate, polyester, and acrylic fibres. The cross-staining of wool by dyes intended for the man-made fibre is considered, with particular reference to blends of acetate and wool; the effect of dyebath conditions, e.g. pH and temperature, is referred to and methods are outlined for minimising staining. Some three-fibre blends are then briefly considered. Finally, possible future developments, with particular reference to blends, are discussed.