Preparation And Application Of Multifunctional Protective Liquid For Paper-based Material

Paper-based artifacts are the precious cultural relics of mankind and the most authentic record of history.However,due to changing external environmental conditions,these precious paper-based artifacts have undergone irreversible aging and damage over time.The anti-aging protection and reinforcement has become an important task for the paper-based materials.There are many factors that cause paper aging and degradation,of which photoaging is an important one.In this paper,titanium dioxide（TiO₂）was used as the UV shielding material in the multifunctional protection liquid for the paper-based materials.Modification of the commercial rutile TiO₂ was conducted by inorganic coating combined with silane coupling.Three-dimensional urchin-like micro/nano-TiO₂was prepared by one-step hydrothermal method.The UV shielding properties of both TiO₂ were investigated.Results showed that the later has good dispersibility,high UV absorption and low photocatalytic performance,and the later is more suitable for the protection of paper-based materials.Then,the Cellulose acetate butyrate（CAB）,hydroxypropyl methyl cellulose（HPMC）,hydroxypropyl cellulose（HPC）,ethyl cellulose（HEC）,sodium carboxymethyl cellulose（CMC）,sodium alginate（SA）and self-made styrene acrylic emulation（SAE）were used to reinforce the paper-based materials.The effect of reinforcement on the paper tensile strength,whiteness,thickness and air permeability were explored.Combining with the comprehensive performance before and after dry heat accelerated aging and UV light accelerated aging,the polymer that can be used for reinforcement was optimized and selected.The results showed that the internal fibers were thickened and the bonding strength between the fibers was increased after being reinforced.The wetting and spreading of the reinforcing agent on the paper pattern effectively filled the gap between the fibers,so that the area between the air and fibers was reduced,which provided a good protection for the paper material.At the same time,the reinforcing effect of the reinforcing agent was related to the degree of spreading on the paper surface and the bonding strength with the fiber.Based on the above,the self-made SAE,HPMC solution and TiO₂ by hydrothermal method were formulated in a certain ratio to prepare multifunctional protective liquid.The influence of protective solution on the tensile strength retention,mass loss and color difference before and after aging was investigated.It was found that the optimized condition was as follows,the micro/nano-TiO₂ dosage was 1 wt.%,the mass ratio of HPMC to SAE was 7:3.The dry heat aging performance indicated that the tensile strength loss of paper after being treated with protective solution was reduced from 43.2%to 95.18%,the mass loss rate was decreased from 18.1%to 8.89%.It could be seen from the results of UV light accelerated aging of reinforced paper that the lowest color difference before and after aging was 0.5 NBS,when the dosage of hydrothermal micro/nano-TiO₂ was 1.0 wt.%.Compared to the paper without reinforcement,the texture of the paper after being treated with multifunctional protective liquid almost remained the original appearance,which met the requirements for paper-based material protection.