Anti-crease Finishing With High Strength Retention Of Cotton Fabrics Based On Disulfide Bridge Cross-linking

As a natural cellulose fabric,cotton fabric is favored because of its advantages such as comfort,softness and good air permeability.However,due to the shortcomings of easy creasing and difficult recovery of cotton fabric,it affects the performance of the fabric and causes many inconveniences in daily use.In response to the crease problem of cotton fabrics,researchers have proposed the use of cross-linking agents for anti-crease finishing of fabrics,but there are many problems such as higher strength loss.In this paper,?-lipoic acid(ALA)was used as the anti-crease finishing agent,and the hydrophilic anti-crease cotton fabrics with high strength retention were finished by organic solvent method,wet finishing,dry finishing or combined with?-mercaptopropyl triethoxysilane(MPTES).Firstly,the grafting of ALA on cotton fabric in organic solvent was carried out,and then the disulfide bond was recombination by sodium borohydrate(NaBH₄)reduction and oxidation in air.The grafting rate of ALA on cotton fabric was calculated by thiol content test.The effect of crease-resistant finishing on color and washable property of dyed cotton fabric was evaluated by K/S value and color characteristic value test.Fourier transform infrared spectroscopy(FT-IR),hydrogen nuclear magnetic resonance spectroscopy(¹H-NMR),differential scanning calorimetry(DSC)and matrix assisted laser desorption-ionization time of flight mass spectrometry(MALDI-TOF MS)were used to investigate the possible anti-crease mechanism.The results showed that the degree of polymerization of oligo-lipoic acid formed by ALA on cotton fabric was 5-10.The concentrations of ALA and Na BH₄were optimized by experiments.The crease recovery angle(CRA)of the cotton fabric after finishing is 250.32°,and the tensile strength retention rate reaches 106.1%.The anti-crease cotton fabric has good wetting performance,and it only takes 4.25 s for the droplets to completely wet the fabric.After 20 standard cycles of washing,it still has good anti-crease performance.Then,in order to avoid the use of organic solvents,according to the water soluble property of ALA when reduced to dihydrolipoic acid(DHLA),wet state finishing based on one-step cross-linking and dry state finishing based on esterification and cross-linking were proposed.Fourier Infrared Spectroscopy(ATR),Scanning Electron Microscopy(SEM)and Energy Dispersive X-ray Spectroscopy(EDX)tests show that there are more oligomeric lipoic acid attached to the cotton fiber on the wet-finished cotton fabric,but the distribution is not uniform.There is no covalent bond connection with cotton fabric by wet finishing,while the dry finishing can make the oligomer lipoic acid uniformly form a coating and bond on the cotton fiber by the way of ester bond connection.The anti-crease cotton fabric finished by the two methods both has good hydrophilicity and the droplet can completely wetting the cotton fabric in 2 s.The effect of different concentration of ALA on the properties of anti-crease cotton fabrics was discussed.The anti-crease effect of cotton fabrics after wet finishing was not ideal.However,when the concentration of ALA was 140 g/L,the curing temperature was150?,and the time was 180 s,the crease recovery Angle was 215.84°,the strength retention rate was 84.7%.Moreover,the anti-crease cotton fabric with dry finishing has better washing property.Finally,the anti-crease effect of cotton fabric was improved by the combination of ALA and MPTES,and the anti-crease finishing of cotton fabric was completed by two steps of curing and steaming.First,the hydrolyzed MPTES were grafted onto the cotton fabric under the curing condition,and then the ALA was finished onto the cotton fabric by steam.ATR,Raman,SEM and EDX tests proved that the new cross-linking system of MPTE-ALA can form inorganic and organic hybrid layer with Si-O and C-S-S-C as the main body on the surface of cotton fiber.The optimal finishing concentration of MPTES and ALA was investigated respectively,and the process of the steaming was optimized.The results showed that the optimal steaming condition was 120? for 30 min,the crease recovery angle of cotton fabric was 231.76°,and the tensile strength retention rate was 87.8%.And the anti-crease cotton fabric has good feel and hydrophilicity.