Study On The Slow-releasing Technique Of Functional Factors And Its Application In The Fragrant And Healthcare Functional Finishing Of Textile Based On Sol-gel Method

As a kind of preparing and modifying technique of material, sol-gel technique has already become a new developing trend of functional finishing of textile due to its characteristics of highly chemical homogeneity, easily processing, high purity, easily shaping & modifying, nontoxicity and inertness to organism, etc. As a kind of colloidal material most widely used, it has been widely applied to functional finishing of textile as excellent eco-friendly finishing material. Any functional factors can be embedded into silica gel by forming film of sol, and to aim to control its release, we can change the structure of film and size & size distribution of its microhole to tailor the immobility of factors, by which textile with long-term functionality can thus be fabricated, such as long-term fragrant and healthcare textile.In regard to this, the purposes of this paper are to prepare eco-friendly stable transparent homogeneous silica sol with good film-forming characteristic and little influence on the properties of treated fabric by sol-gel process using tetraethoxysilane (TEOS) as precursor, (y-glycidyloxypropyl)-trimethoxysilane (GPTMS) as modifier, ethanol as co-solvent, hydrochloric acid as catalyzer, poly (vinyl alcohol) (PVA) as film-forming accelerant and to fabricate long-term fragrant and healthcare textile by embedding lavender essence having calming and nerves-soothing effects into silica sol and forming film on the surface of fabric, and to try to develop a new finishing technique with simpler and more eco-friendly process for fragrant and healthcare functional finishing of textile. Thus, the main research contents and results of this paper are as follows:Firstly, in this paper, we investigated the influences of dosages of water, co-solvent (ethanol), catalyzer (hydrochloric acid), film-forming accelerant (PVA) & modifier (GPTMS) and reaction temperature & time on the properties of the obtained silica sol (viscosity, gelation time and size of colloidal particle) by single factor experimentation, and optimized the processes using orthogonal design [L)6(45)] and analyzed the influence of modifier on the morphology of silica film. The results show that stable transparent homogeneous silica sol with good film-forming characteristic and little influence on the properties of treated fabric can be obtained under the conditions that molar ratios of TEOS to H2O to Ethanol to HCl to GPTMS is 1:50:8: 8×10-3:1, concentration of PVA is 0.2% and reaction temperature & time are respectively 25℃and 3 h. The analysis of SPM indicates that modified silica film is thinner and more homogeneous than silica film not modified.Secondly, we prepared lavender-embedded silica and modified silica gel based on the processes above, and investigated the releasing properties of the two gels in 95% ethanol solution and made a kinetic model fitting, and also characterized the two gels by TG and FTIR. The results show that both silica gel and modified silica gel have slow-releasing effect on lavender essence inside and silica gel not modified is comparatively better. Adding modifier (GPTMS) will reduce the slow-releasing effect of silica gel, but will not change its releasing mechanism. The release mechanism of lavender-embedded silica gel accords with Higuchi model, which suggests that the release of functional factors inside is realized by diffusing through gel network and cavity. The analysis of TG testifies that the slow-releasing effect of modified silica gel reduced due to the addition of GPTMS, and the analysis of FTIR indicates that the embedding process is only physical mechanism, not influence the properties of substances loaded.Thirdly, long-term fragrant and healthcare textile was fabricated using the finishing solution containing lavender essence incorporated with silica sol or modified silica sol, and the influences of finishing method, baking conditions, mass ratio of lavender to SiO2 and modifier on fragrance retention time of the treated fabric were investigated, furthermore, the influence of modifier on washing fastness and mechanical properties of the treated fabric was also investigated, and the treated fabric was characterized by TG, DSC, FTIR, SEM and SPM. The results show that fragrance retention time of the fabric treated by dip-pad method is longer than that by immersion method. Baking conditions have remarkable influence on both fragrance retention time and aromaticity, the reasonable baking conditions are 120℃of baking temperature and 1 min of baking time. The mass ratio of lavender to SiO2 also has obvious influence on fragrance retention time and the optimized ratio is 1:2. Adding modifier reduced the slow-releasing effect of the treated fabric, but improved washing fastness and reduced the negative influence on the properties of the treated fabric. The heat-decomposing property of the treated fabric changed little compared with the untreated one. Glass transit temperature (Tg) of the treated fabric enhanced, and Tg of the fabric treated with modified silica sol is a little lower than that with silica sol not modified. SEM shows that the continuous silica film was formed on the surface of the treated fiber. The analysis of SPM indicates that the formed gel network from modified silica sol is looser than that from silica sol not modified.Lastly, the influences of treatment of acid-catalyzed silica sol derived from TEOS on the tensile strength, tear strength, hand, wicking effect and water vapor transmission & moisture desorption properties of the treated cotton fabric were investigated. The results show that treatment of silica sol on cotton fabric is favorable to the improvement of its tensile strength under certain conditions, especially at higher curing temperature or for longer curing time, certainly, the temperature must be strictly controlled in the range in which the fiber will not be damaged. The tear strength, wicking effect and water vapor transmission property of the treated cotton fabric all decreased at different levels, especially at higher curing temperature, or for longer curing time, or with higher silica content, whereas the addition of GPTMS can reduce the negative effect of the treatment on theirs, especially in a lower molar ratio of TEOS to GPTMS. The hand of the treated cotton fabric decreased, especially at higher curing temperature, or for longer curing time, or with higher silica content, whereas the addition of GPTMS can weaken the negative effect of the treatment on hand, especially in a lower molar ratio of TEOS to GPTMS. The moisture desorption property of the treated cotton fabric decreased, especially at lower curing temperature, or for shorter curing time, or with lower silica content, and the addition of GPTMS has not remarkable effect. The analysis of ATR-FTIR shows that the treatment of silica sol has not distinct influence on the microstructure of the treated fiber.