Study On Softening Of Fly Ash/Coal Gangue Fiber And Its Effect On Paper Properties

This research is commissioned by the enterprise to soften fly ash/coal gangue fiber which is producted by fly ash, coal gangue that came from the coal combustion, coal washing industry recovered solid waste. In papermaking use the soften fiber, and study its effect on paper properties. The purpose was to make fly ash/gangue fiber be more suitable for the papermaking industry, in order to achieve the purpose had to do the following three aspects:(1) Study on softening process of cetyl amino acids fabric softener (CAA) to fly ash/coal gangue fiber and its effect on paper propertiesFly ash/coal gangue fiber has less surface groups, rigidity, brittleness, easy-breaking, and fibers combining ability is poor. The composite paper properties are very poor which directly produced by fly ash/coal gangue fiber, so need to soften the fiber and improve the utilization value of the fiber. With the cetylamine as the main raw material, a kind of amphoteric surfactants was synthesized by carboxylation reaction, it was named that cetyl amino acids fabric softener (CAA), which changes the fiber surface potential by adsorption, and simultaneously the aliphatic branched hydrophobic group was introduced, in order to softening the fiber. The fiber was characterized by X-ray diffraction spectrometer (XRD) and composition analysis, and the SEM was analyzed the softening results. The softener was characterized by Fourier transform infrared spectrometer (FT-IR), and used it to soften the fly ash/coal gangue fiber, then evaluated the consequents of softened fly ash/coal gangue fiber by method of slag loss rate, sensory evaluation of fiber softness and sensory evaluation of fiber strength, and to get the optimum softening process. Its effect on paper properties were studied by papers made of softened fly ash/coal gangue fiber and plant fiber. The results showed that the optimum softening process was that softener dosage was 0.5%, the pH was 6 and softening 30 min. When the filling amount of soften fly ash/coal gangue fiber was 10%-20%, the properties of the composite paper even better than the pure plant paper.(2) Softening of fly ash/coal gangue fiber by two kinds of mixed surfactant system and its effect on paper propertiesWhen the cetyl amino acids fabric softener (CAA) was used to soften the fiber, the sensory evaluation of fiber softness was improved directly, the soften fiber hands feeling soft satiny, but the slag loss rate of the fiber was still high, and the utilization rate of the fiber was poor. In order to further improve the softening effect of fiber, choosing two kinds of mixed surfactant system, cetyl amino acids fabric softener (CAA)+dodecyl betaine (BS-12) and cetyl amino acids fabric softener (CAA)+ cetyl trimethyl ammonium bromide (CTAB) to soften the fiber. Study the optimum softening process of the fly ash/coal gangue fiber and its papermaking performance. The results showed that:a. under the condition of pH= 6,choosing 0.25% CAA and 0.6% BS-12 to mixed and softening 50 min was the optimum softening process, and when the dosage of softened fiber was 30%, the tensile strength of CAA+BS-12 increased by 55.0%, the ring crush strength increased by 29.7%; b. under the condition of pH= 6,choosing 0.25% CAA and 0.15% CTAB to mixed and softening 60 min was the optimum softening process, and when the dosage of softened fiber was 30%, the tensile strength of CAA+CTAB increased by 45.2%, the ring crush strength increased by 25.7%. In general, the softening effect of CAA+BS-12 much better in these two kinds of mixed surfactant system.(3) Research on the properties of softening and strengthen fly ash/coal gangue fiber and composite paperThe softening fly ash/coal gangue fiber had overcome the shortcomings of rigidity, brittleness, easy-breaking, but it still has less surface groups, and its surface is smooth, fibers combining ability is poor, those disadvantages will directly impact on paper strength, polyvinyl alcohol-Al2(SO4)3 (PVA-Al2(SO4)3) fiber reinforced modifier is a kind of cationic fiber reinforced modifier which synthesized by polyvinyl alcohol (PVA), a good film material. With the reinforced modifier strengthen the fiber, it can form a layer coated on the fiber surface, effectively improve the surface of the fiber morphology, enhanced the bonding force between the fibers and further improved the properties of composite paper. The compound softener which is dodecyl dimethyl betaine (BS-12) and self-made cetyl amino acids (CAA), modifier which is polyvinyl alcohol-Al2(SO4)3 (PVA-Al2(SO4)3) were used to change fly ash/coal gangue fiber. The changes of the fiber were observed by the Zeta potential and Scanning Electron Microscopy (SEM). Through the fly ash/coal gangue fiber and plant fiber composite paper properties test to investigate and discuss the fiber that treated by different means. The results show that, the performance of the composite paper will be greatly improved by using the treated fly ash/coal gangue fiber in papermaking. When the filling amount of softening fiber is 20%, or the filling of softening modified fiber is 30%, the performance of the composite paper can completely reach the standard of pure plant fiber paper.