Moisture Absorption And Permeability Of Biomass Modified Unfigured Sea-island Superfine Fiber Synthetic Leather Base

Sea-island superfine fiber synthetic leather belongs to high-grade simulated leather. It has many characteristics and advantages of natural leather. And its mechanical strength, chemical resistance and homogeneity are better than that of leather. Compared with leather, the wearing comfort of superfine fiber synthetic leather is worse due to its poor moisture absorbption and permeability. Therefore, the study on moisture absorption and permeability of superfine fiber synthetic leather has become a hot topic.According to different processes, the sea-island superfine fiber synthetic leather base is divided into two types which are figured and unfigured sea-island. In this study the unfigured sea-island superfine fiber synthetic leather base (USFSLB) was as raw material. Through the surface modification, the biomass materials, collagen was grafted on the polymide superfine fibers of USFSLB to improve the moisture absoption and permeability. The collagen was extracted from leather wastes. According to the corsslinkining ways of collagen with polyamide fiber, hydrogen/coordination bond, surface coating and covalent bond crosslinking were studied. The brief research content revolving around the three points are as follows.Firstly, chrome tannins as crosslinking agent was used to crosslink the collagen with polyamide fiber of USFSLB for improving the moisture absorption and permeability. The modification method was divided into three steps. The first step was washing pretreatment; the second step was sulfuric acid hydrolysis; and the third step was C-CrT grafted USFSLB. Through the single factor/orthogonal experiments, the optimum reaction conditiona were decided. The dodage of sulfuric acid was 15% of dry USFSLB. The liquid ratio of third step was 1500% of dry USFSLB. The best penetration time of collagen was 3h. The dosage of chrome-tannins was 5% of dry USFSLB. The best crosslinking temperature and time of chrome-tannins was 60℃ and 3h respectively. The moisture absorption and permeability of modified USFSLB was improved rapidly. Compared with untreated USFSLB, the static water-vapour transmission rate (SWVT) and liquid wicking rate (LWR) of modified USFSLB increased greatly. On the premise of not affecting the tensile strength and elongation at beak of untreated USFSLB, the thickness, eveness and antistatic were improved.The result of water contant angle showed that, the USFSLB surface was changed from hydrophobicity to hydrophilicity. While the SEM/EDS, AMF, ATR-IR, TEM and XPS analysis indicated that collagen-chrome tannins were grafted on USFSLB in the form of microspheres. Finally, the Cr escape experiment from modified USFSLB was studied, which showed that the Cr escaping was far less than the standard of GB/T 18882-2009.Secondly, methacrylanide modified collagen (CMA) was prepared by the reaction of collagen with methacrylic anhydride. Through single-factor/orthogonal experiments, the optimal experimental conditions was that the temperature was 50℃, reaction time was 2h, the dosage of methacrylic anhydride was 30% of dry collagen. The characterization of 1H-NMR and FT-IR showed that the vinyl was modified on the collagen successfully. Then the film-forming of crosslinked CMA was researched, which was that ultraviolet irradiation time was 3h in the UV device with 50W,365nm,34cm×26cm×15cm of exposure chamber, initiator concentration of the CMA solution was 0.005%～ 0.01%, the substitution degree of vinyl-modified collagen was 73%. The characterization of SEM, ESEM and FT-IR showed that the C=C of vinyl-modified collagen was initated polymerization, and the films was water insoluble.Then, the film-forming conditions of CMA were applied on the surface modification of USFSLB to make CMA form membrane on the surface of polyamide fibers and get USFSLB/CMA. The optimal conditions of preparing USFSLB/CMA were as follows:UV irradiation time was 3h in the UV device with 50W,365nm,34cm×26cm×15cm of exposure chamber, initiator concentration of the CMA solution was 0.06%and vinyl-modifed collagen substitution degree was 83%. The SWVT and LWR of USFSLB/CMA increased by 32.6% and by 477.7%.Thridly, pure polyamide fibers were as the research models of USFSLB, the hydroxylation-modified polyamide fiber (Nylon-OH) and thiol-modified polyamide (Nylon-SH) was studied step by step. By single-factor/orthogonal experiments, the optimum preparation conditions of Nylon-OH were that the reaction temperature was 60℃, dosage of formaldehyde was 4068% of dry Nylon, and the dosage of phosphoric acid was 3% of formaldehyde, reaction time was 15h,. While for Nylon-SH, the optimal reaction temperature was 70℃, dosage of (3-mercaptopropy)-trimethoxysilane (MPS) was 285% of dry Nylon, the reaction time was 12h. The mol ratio of SH with OH was 10:1. The results of water contact angle, SEM, AFM and XPS, ATR-IR proved that the hydroxyl and thiol were successfully introduced on the surface of polyamide fibers. According to the optimum preparation conditions of Nylon-OH and Nylon-SH, the preparation of USFSLB-OH and USFSLB-SH were studied. The optimal conditions of USFSLB-OH were as follows:the dosage of formaldehyde was 900% of dry USFSLB, and the dosage of phosphoric acid was 3% of formaldehyde, the reaction temperature was 60℃,reaction time was 15h. The hydroxyl on USFSLB was 0.Olllmmol/g. The optimal conditions of USFSLB-SH were as follows:reaction time was 12h, temperature was 70℃, dosage of MPS was 4.5%～6.3% of dry USFSLB. The thiol on USFSLB was about 0.075mmol/g. After calculated, the mol ratio of thiol and hydroxyl SH/OH was 8:1. At the same time, LWR and SWVT values of USFSLB-OH increased, and the LWR value of USFSLB-SH reduced. This phenomenon showed that polyamide fiber surface of USFSLB had been modified with hydroxyl and thiol successfully.The grafting of Nylon-SH by CMA was researched according to the thiol-ene "click chemistry". The double bond on the collagen can react with thiol of Nylon-SH by UV irradiation, which can make the collagen graft on the surface of polyamide fiber in the form of a covalent crosslinking. The best conditions of grafting modification was that in the UV device with 50W,365nm, 34cm×26cm×15cm of exposure chamber, ultraviolet irradiation dose was 30kGy irradiation time was 5h～6h, initiator concentration of CMA solution was 0.005%～0.015%, substitution degree of vinyl-modified collagen was 73%～ 79%. The water contact angle measurement, ATR-IR and XPS analysis confirmed that the CMA was grafted on the surface of polyamide fiber successfully. According to the optimum grafting condition of CMA with Nylon-SH, the CMA grafted USFSLB-SH (USFSLB-S-CMA) was researched. Results showed that UV irradiation time was 5h in the UV device with 50W, 365nm,34cm×26cm×15cm of exposure chamber, concentration of initiator was 0.006%. Compared with untreated USFSLB, when the substitution degree of CMA was 50%, the SWVT of USFSLB-S-CMA was increased by 43%, and when substitution degree of CMA was 73%, the LWR of USFSLB-S-CMA was increased by 602.4%.The modification of USFSLB by using waste collage not only improved the moisture absorption and permeability of USFSLB, but also enhanced the added value of product, which can achieve resource recycling. So this study has potential economic and environmental significance. At the same time, the theory about improving the moisture absorption and permeability of USFSLB is expanded and enriched.