Investigation Of The Refining, Dyeing And Finishing Of Jute Fiber

Jute is a natural renewable cellulosic fiber,which has the similar excellent features and special styles as ramie and flax,such as coolness,air permeability,comfortability, excellent moisture adsorption and discharging,biodegradable and so on,but jute also has some disadvantages viz.lower cellulose content,coarseness,stiffness,high rigidity, poor spinnability,et al.Therefore,jute is basically used for traditional purposes such as sackings,ropes,packaging materials and hessian.Recently,although the spinnability of jute fiber has been considerably improved by the cooperative endeavors of researchers, the lower count jute yarns just can meet the demands of upholsters and carpets,which is not suitable for garment textiles.Furthermore,jute and jute blended fabric has poor crease recovery,yellowing and browning tendency,poor deep dyeability and some other disadvantages.Taking account of the above problems,the refining,dyeing and finishing of jute fiber has been studied in this thesis.Firstly,the chemical,enzymatic and combination of chemical and enzymatic treatments were applied to study the refining of jute fiber.The results showed that pre-acid treatment could alleviate the burden of alkali scouring,additives and their dosage had significant effect on breaking intensity and fineness of jute,sodium dithionite bleaching could cooperate with hydrogen peroxide bleaching to improve the whiteness index and fineness,and the combined bleaching of sodium dithionite and hydrogen peroxide could obtain the same efficiency as sodium chlorite bleaching. Pectinase and xylanase had goog synergistic effect,and the refining efficiency could be obviously improved when alkali scouring was carried out before enzyme treatment. After the combination refining treatment,most of the non-cellulosic materials had been removed,and the count and the surface cleanliness of jute fiber were considerably improved.Under a certain treatment condition,the chemical refining treatment would not change the crystalline structure while the crystallinity was improved.And the refining treatments would make the thermal decomposition temperature of jute fiber shift to lower temperature.Pre-treatment of jute fabric is an impotant part of this thesis.The desizing ratio was used to evaluate the effect of acid desizing,alkali desizing,oxidant desizing and enzyme desizing.It was found that Suhong desizyme 2000L was a high effective desizing agent.The pre-hot water treatment was necessary for enhancing the desizing efficiency.After enzyme desizing treatment,favorable desizing ratio could be obtained just through one-step of hot water washing.The optimum desizing processes and conditions as following:pretreatment（JFC 1 g/L,liquid ratio 1:20,temperature 80℃and time 20 min）â†'enzyme desizing（desizyme 0.8 g/L,penetrating agent JFC 1 g/L, neutral pH,kept at 70℃for 45 rain with liquor ratio 1:20）â†'washing（temperature 80℃and time 2 min）.Furthermore,the combination scouring and bleaching in one-bath at lower temperature in the absence of sodium hydroxide was studied. Compared with traditional two-bath-two-step method,the one bath way treated fabric had lower weight loss,higher breaking strength and good wettability（t<1s）.But the whiteness index was poorer for the high whiteness index required or the tint dyed products.The optimal conditions was as follows:scouring agent TA-110 6 ml/L, hydrogen peroxide 7 ml/L,hydrogen peroxide activator TA-116 2 ml/L,JFC 1 g/L, liquor ratio 1:20,temperature 75℃,time 50 min（the treatment time before and after TA-116 addition is 30 min and 20 min respectively）.Another important part of the thesis is to improve the dyeability of jute fabric.The modification of glycidyl trimethyl ammonium chloride（Glytac） and its effect on the deyeabilities of jute fabric were studied.The results showed that Glytac modification could reduce the dosage of salt and alkali during the reactive dyes dyeing process and down dyeing temperature,increase dye utilization rate,build-up,washing fastness and rubbing fastness while the light fastness and the dyeing levelness were not affected.The optimal Glytac modification conditions was as follows:Glytac 40 g/L,sodium hydroxide 8 g/L,JFC 2 g/L,kept at 60℃for 45 min with liquor ratio 1:20.The results of dyeing thermodynamic and dyeing kinetic indicated that the adsorption isotherm of Glytac modified fabric fit well with Langmuir model,and the adsorption ability was correspond with the Pseudo second-order kinetic model（R²>0.9945）.The dyeing process of the modified jute fabric with reactive dyes is an exothermic reaction. The adsorption rate was accelerated when the dyeing temperature increased,but the equilibrium adsorption value and affinity reduced.The effect of enzymes and softening agents on the softness and prickle of jute fabric were studied.Although enzymes and softening agents could improve the softness and alleviate the urtication feeling,it could not be completely eliminated.The softness of jute fabric could be further improved when the softening agent treatment was carried out after enzymatic treatment,and the urtication feeling could be completely eliminated. Compared with neutral cellulase and alkali cellulase,acid cellulase（Cellusoft L） was the most effective enzyme for improving the softness and prickle sensation of jute fabric. And the optimum treatment condition was as follows:Cellusoft L 3.0%（o.w.f）,JFC 2 g/L,pH value 4.8,liquor ratiol:10,temperature 50℃and time 60 min.Moreover, ammo silicone oil 8040 is a favorable agent for jute fabric softening finishing,the optimum conditions for 8040 treatment was obtained as following:8040 15 g/L,JFC 2 g/L,pick-up 90%,pre-dry temperature 80℃and time 3.0 min,baking temperature 150℃and time 3.5 min.When glyoxal was applied as crosslinking agent to improve jute fabric morphological stabability.Magnesium chloride（MgCl₂） was an effective catalyzer for the reaction between glyoxal and cellulose.MgCl₂ could reduce the baking temperature,but had negative effect on the breaking strength.The breaking strength could be improved when triethanolamine（TEA）,chitosan and sodium hypophosphite（NaH₂PO₂） was applied respectively,while the wrinkle recovery angle（WRA） obviously decreased.The breaking strength could be significantly improved with little effect on WRA When TEA, chitosan and NaH₂PO₂ were applied in one bath.Furthermore,both the breaking strength and WRA increased when ammo silicone oil was applied.The conditions for glyoxal treatment were optimized as following:glyoxal 60 g/L,MgCl₂ 60 g/L,chitosan 0.8 g/L,NaH₂PO₂ 24 g/L,TEA 10 g/L,ammo silicone oil 8040 20 g/L,pick-up 100%, pre-dry temperature 90℃and time 3 min,baking temperature140℃and time 3 min.