Research And Application Of Reactive Cationic Waterborne Polyurethane Fixing Agent

In recent years,with the improvement of consumers’ requirements for bright color,warmth and comfort,the color fastness of dyed fabrics has been raised to a higher standard.Although a stable covalent bond can be formed between cotton fabric and fiber when dyed with reactive dyes,due to the formation of hydrolytic groups,there are some defects such as low wet rubbing fastness,easy fading after washing and so on.The formaldehyde free fixing agents on the market still can not improve the friction fastness,so the new fixing agents are still the research hotspot.Some closer years come,waterborne polyurethane has been applied more and more prominently in textile and clothing finishing.It is a composite emulsion formed by water as a medium,and has the advantages of green environmental protection,formaldehyde free and safety.It is found that cationic waterborne polyurethane has fixation effect on reactive dyes and direct dyes,and can improve the color fastness of fabrics.Therefore,the research and development of cationic waterborne polyurethane has a broad application prospect.The preparation and application of different types of cationic waterborne polyurethane fixing agent were studied by prepolymerization.Polyethylene glycol(PEG molecular weight 1000),polyester 218(molecular weight 1000)and isophorone diisocyanate(IPDI)were selected as the basic raw material.N-MDEA was used for chain extension.TMP was used for crosslinking.Benzyl chloride was used for cation ionization.MEKO was used for termination protection,and water emulsion was used to prepare cationic waterborne polyurethane(CWPU).Through the fixation finishing of dyed fabric,the best fixation finishing technology is explored.Fourier transform infrared spectroscopy(FTIR),thermogravimetric analysis(TGA)and differential scanning calorimetry(DSC)was used to analyze the chemical structure,thermal stability and thermal transformation properties of CWPU film.The performance of cationic waterborne polyurethane emulsion was characterized by particle size test and viscosity test.The effect of color fixing agent on the whiteness,shade and hydrophilicity of cotton fabric was studied.The effects of prepolymerization temperature and time,polyester polyether ratio,R value(-NCO/-OH),chain extender and crosslinker on the properties of cationic waterborne polyurethane were analyzed.The optimum preparation conditions were optimized by FI-IR spectrum,particle size analysis,thermodynamic performance analysis and fixation effect.The results show that the best synthesis process of CWPU fixing agent is: R value is 2,polyethylene glycol(PEG)/ polyester 218 is 4:1,N-MDEA dosage is 4%,MEKO dosage is100%,and the synthesized CWPU emulsion has better appearance and performance.The average viscosity of CWPU emulsion is 29 m Pa·S,and the solid content is 28±2%.The best fixation finishing process of color fixative CWPU is: two soaking and two rolling(the dosage of color fixative is 160 g / L,the rate of rolling liquid is 80%),prebaking at 80 ℃,baking at140 ℃,p H value is 6-7.The color fixing effect of unsealed CWPU is better than that of DM-2589 and color fixing agent 1.Compared with untreated fabric,the color difference of direct dye dyed fabric is less,the dry friction fastness is increased by 1.5,and the wet friction fastness is increased by 1.However,for reactive dyes dyed fabrics,although the color difference has a certain impact,the wet rubbing fastness is increased by 1 level to 3-4 level,and the fastness to cotton staining,wool staining and fading can be increased by 0.5-1.5 level.After finishing with closed type CWPU,it is found that the reactivity of fixing agent has been improved,the color fastness of reactive dyes has been further improved,the dry friction fastness has reached4-5,and the wet friction fastness has also reached 4.After finishing with CWPU,the whiteness and wool effect of the fabric have little influence,and the handle of color light has a certain influence.The fabric after treatment has stronger tensile strength than the original fabric.CWPU was synthesized by the best preparation technology determined in this project.It has the advantages of water as solvent,simple process,environmental protection,good filmforming performance,and the effect is better than the market fixative.Therefore,this subject is an experimental study with a prospective significance.