| Paper artifacts as a heritage with a recorded function,reflects really and vividly the characteristics and splendid culture during various periods,and has the precious history,art and scientific value.However,in the process of long-term preservation,paper artifacts have come into being serious diseases which have irreversibly damaged the paper artifacts and writings,due to their own materials and the external factors such as light,temperature,water,acid and alkali chemical reagent effects,causing the original information blurred or even disappeard.Therefore,the protection and repair of paper artifacts is a very important research topic.The appearance of archives and the prevention and control of the handwritings are important research contents for paper workers.At present,paper workers of Shaanxi Normal University,Ministry of Education Historical and Cultural Heritage Protection Engineering Research Center have successfully developed the method of the LC protective agent(first reinforcing agent:phosphoric acid and phosphotungstic acid in ethanol or acetone solution;secondary reinforcing agent:saturated barium hydroxide solution)to reinforce the ink writings.The method is characterized by the simple operation process,the remarkable effect of anti-bleed,the durability of the paper can be improved,and has been successfully applied to the archiving of the archives.However,the exact mechanism of the method is not clear.Therefore,this paper has taken the direct sky blue 5B and the ink writing materials as the research object and anti-bleed processing process as the basis to reveal the mechanism of the barium phosphotungstate against ink writeoff and the mechanism of anti-ultraviolet radiation.The main contents of the thesis include the following aspects:1.The behavior researches of the direct sky blue 5B adsorbed by the barium phosphotungstateIn this paper,the adsorption behavior of barium phosphotungstate on the direct sky blue 5B in the solution system was studied in the light of the possible role of barium phosphotungstate insoluble precipitate adsorption in the dye bleaching.The effects of the corresponding factors on the adsorption behavior were obtained by adjusting the pH value of the system,barium phosphotungstate and direct sky blue 5B,and barium phosphotungstate precipitation conditions by UV-Vis,SEM and EDAX.The results show that the protonation of the direct sky blue 5B molecule,the coprecipitation of the dye with barium phosphotungstate,and the barium phosphotungstate with small particle size are favorable to the direct sky blue 5B adsorbed by barium phosphotungstate.2.Studies on the interaction of phosphotungstic acid with dye and the mechanism of anti-UV fadingBased on the interaction between phosphotungstic acid anions and proton dyes and the archival protection practice of phosphotungstic acid ethanol or acetone solution as a reinforcement to reinforce the writing,it is presumed that barium phosphotungstate precipitation may be related to the electrostatic interaction of phosphotungstic acid anions with dye molecules.At the same time,heteropoly acid anions can absorb ultraviolet light and under certain conditions with a reversible photochromic nature,therefore,barium phosphogluconate protection against UV light may be related to the above-mentioned optical properties of phosphotungstic acid.Based on the above speculation,the effects of UV-irradiation,irradiation time,concentration of phosphotungstic acid and different atmospheres on the UV-Vis spectra of the direct sky blue 5B were investigated and the mechanism of anti-ultraviolet light fading of phosphotungstic acid dyestuffs was explored.The results show that Ultraviolet light irradiation can make the azo chromophore and aromatic ring of direct sky blue 5B damage,so that it fades;phosphotungstic acid has a strong absorption of ultraviolet light,which has the effect of inhibition of UV-light on the degradation of direct sky blue 5B;the effects of air,oxygen and nitrogen on the degradation of dyes by UV-irradiation are different.This difference is related to the difference in oxidative activity species produced by UV-irradiation in different atmospheres,which is related to the presence of microbubbles in the solution.3.Studies on the ink handwritings of the diffusion and inhibition of Ultraviolet irradiation on paperIn order to reveal the mechanism of ink diffusion prevented on paper and to inhibit the mechanism of ultraviolet light irradiation,based on the adsorption of barium phosphotungstate on the direct sky blue 5B in the above solution and the inhibitory effect of phosphotungstic acid on degradation of direct sky blue 5B by UV Irradiation,this part has taken paper as carrierhas and made use of macroscopic representation and SEM characterization to research the effects of the amount of barium phosphotungstate precipitate,the reaction ratio of phosphotungstic acid and barium hydroxide,the types of ink,the ways of precipitation and the pH of the medium on the photographic characters of ultraviolet radiation,having discussed the photochromic mechanism of phosphotungstic acid and barium phosphotungstate.The results show that:(1)The appropriate amount of adsorptive precipitation and coprecipitation have good resistance to ink writings;(2)The effect of barium phosphotungstate on the different types of ink is different and under the same conditions the anti-bleeding effect of blue ink is the strongest,followed by black ink,but red ink is the worst;(3)Barium phosphotungstate has a positive effect on the inhibition of UV radiation degradation of dyes,which is related to the absorption of ultraviolet light from barium phosphotungstate coated dyes.(4)Whether phosphotungstic acid produces photochromic phenomena is closely related to its pH.In the range of 1.8<pH<3.6,phosphotungstic acid has occurred photochromic phenomenon,but in the range of 3.6<pH<4.1,phosphotungstic acid has not occurred photochromic phenomenon,which is related to the changes of phosphotungstic acid composition at different pH conditions. |
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