| Transparent water color rendering was used generally in watercolor painting,due to the characteristics of transparent color,the light color can not cover the dark,but only dark overlap the light-colored.So the characteristics of watercolor painting skills and difficulties were leaving blank.For a long time,people have tried a variety of methods: pasting the adhesive tape,covering with film,using knife and white powder painting,the use of these methods was easy to damage the paper.With the continuous exploration of people,researchers found a method of leaving blank by using the white glue where the blank was needed,and had achieved initial results.But the white liquid currently used in the market was latex,there were two main problems: Firstly,it was difficult to peel off on paper.Secondly,not timely washing,will be formed a layer of film in the pen and difficult to remove,so that watercolor pen was damaged.In this paper,water-based long-chain acrylic polymer emulsion was prepared as a new stripping agent,mixed with natural latex to solve these problems.The long-chain acrylic polymer was used to reduce intermolecular force between the natural latex film and paper-based material.At the same time,surface of the brush was not easy to adhere to the polymer because of the introduction of small molecule surfactants and easy to wash away the residual rubber.The preparation methods and application properties of long chain acrylate polymers and corresponding aqueous polymer emulsions were discussed and the effects of the amount of different solvents,the amount of initiator,the stirring speed,the polymerization temperature and the polymerization time on the conversion of the monomer in the process of long chain acrylate polymer were also discussed.The structures of the obtained products were characterized by attenuated total reflection Fourier transform infrared spectroscopy(ATR-FTIR),gel permeation chromatography(GPC)and nuclear magnetic resonance(NMR).The stability,viscosity,particle size and rheology of the emulsion were tested by centrifuge,particle size analyzer,dynamic rheometer and the tensile strength,elongation at break,180° peel strength,water absorption and salt solution,pencil hardness,etc.were also observed.The main research contents were as follows:The polyacrylic acid octadecyl ester polymer was synthesized by solution polymerization under the condition of cyclohexane as the dispersed phase,the long chain acrylic acid octadecyl ester as the main polymer monomer and azobisisobutyronitrile(AIBN)as initiator.Orthogonal experiment was established to get optimum technological of polymerization.The structures of products were characterized by Fourier transform infrared spectroscopy(FTIR),Nuclear magnetic resonance(NMR),gel-chromatography(GPC).The optimum polymerization conditions were obtained by the yield of product: polymerization temperature 80?,cyclohexane dosage 60%,initiator ratio 0.5%,polymerization time 4h.Non-ionic acrylate emulsion was prepared with Phase Inversion Emulsification(PIE)and the effects of different types of emulsifiers on the properties of the emulsions were analyzed,and the emulsifiers with the most suitable emulsification were screened out.The optimum process of preparing acrylic polymer emulsion was screened by orthogonal test,and the stability,particle size and viscosity of emulsion were selected.The results showed that the emulsion produced by the combination of sorbitan oleate(Span 80)and peregal(O20)with an HLB value of 10.5 had better performance.The amount of compound emulsifier was only 6%.The orthogonal experiment results showed that optimum conditions were,emulsifying time 20 minutes,emulsifying temperature 80?,stirring rate 300 rad/min and emulsifying water was added by three times.The acrylate emulsion was prepared under this condition,emulsion particle size distribution range was 0.1~0.4?m,viscosity was 20s(measured by the coating-4 cup),centrifugal stability was 99.8%.The results of dynamic rheological tests showed that the prepared long-chain acrylate polymer emulsion was a non-Newtonian fluid,specifically a pseudoplastic behavior,with the nature of shear-thinning.The results of dynamic strain sweep showed that emulsion demonstrated resilience with the strain less than 0.3%,and emulsion demonstrated viscous with the strain more than 0.3%.The surface tension and peeling effect of the emulsion consisted of polymerstripping agent and the water-based natural latex in a certain proportion were measured.The mechanical properties of the film were tested,and the paper before and after peeling was analyzed by scanning electron microscope.The results showed that,when the addition amount of the stripping agent in the natural latex was increased to 12%,the surface tension of the emulsion decreased from 46.7 m N/m to 37.2 m N/m,the average tensile strength 4.225 MPa,elongation at break 940.120%,and the water absorption 12.82%,salt resistant solution over 36 h,peel strength was down to 0.32 kN/m on tinplate.The results of scanning electron microscopy showed that: the natural latex was formed and peeled off on the surface of the paper would tear the fiber of the paper,and after adding the stripping agent to the natural latex,the fiber of paper was not damaged.It was proved that the film formed by adding the release agent to the natural latex was really torn,and it can be washed only with water and the brush was not damaged.The long-chain acrylate emulsion prepared in this experiment can be added as a stripping agent into the water-based natural latex and washed with only water after usage.After Painting on the paper will form a layer of latex film,the film can be peeled from the paper,so as to achieve the effect of white and the blank place can continue to color.Also this will not affect the appearance and use of paper.The stripping agent may also be compounded with other film-forming paints,it can be filmed in the glass,plastic,steel and other surface,which was used to protect the material or equipment and easy to peel. |
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