The Study On The Preparation Of NCR Microcapsules And Their Security Features

Compared with the traditional copy paper, carbonless copy paper is easy to use and isfree of contamination; therefore it is widely used in the invoice, computer bills, and manyother fields. As the main component of carbonless copy paper, the performances ofmicrocapsules largely determine the performance of carbonless copy paper. Due to the wideuse in commercial areas, the demand for security features of the carbonless copy paper isbecoming increasingly high. At present the anti-counterfeiting means of non-carbon papermainly focus on the two aspects of base paper and printing anti-counterfeiting. If theanti-counterfeiting technology and microencapsulation technology were combined to preparethe microcapsules with the security features and used in carbonless copy paper, it would beable to expand the existing anti-counterfeiting technology for better security.In this paper, crystal violet lactone was used as the core material and melamineformaldehyde resin as wall materials, the microcapsules were prepared by in situpolymerization method, the preparation process was optimized through the use of orthogonalexperiments. Based on this, the microcapsules with the security features were prepared byadding fluorescent reagents in them and used in carbonless copy paper. The optimal amountand ratio of the fluorescent reagents were determined by detecting the fluorescence intensity,color density and color aberration of carbonless copy paper. The conclusions were asfollows:1. Two emulsification time and emulsification speed of these three factors were analyzedby the orthogonal experiment, to determine the best preparation process: the firstemulsification time1was35min, the second8min, and the emulsification speed was3200r/min.2. The results of Malvern laser diffraction indicated that the particle sizes of themicrocapsules under optimal process were in the3-10μm range and with a narrowdistribution. The results of scanning electron microscopy indicated that the microcapsuleswere spherical and without adhesion. Furthermore, the results of DSC, TG and FTIR alsomanifested that the preparation process was successful. The residual formaldehyde contents in the emulsion before and after adding the urea were measured by headspace gaschromatography technique, which proved that the addition of urea could reduce the residualformaldehyde content.3. Based on the optimal preparation process, the microcapsules with the securityfeatures were prepared by adding fluorescent reagents and used in the carbonless copy paper.The results of fluorescence intensity, color density and color aberration of carbonless copypaper indicated that the optimal amount of fluorescent reagents was0.4%(accounting for theproportion of core material solution quality), the optimal process was to be added to thereaction system after being solved in the core solution, the effects of three kinds offluorescent reagents from good to bad were blue, red and yellow fluorescent reagents. Twofluorescent reagent compound experiments proved that the best compound was the red andblue fluorescent reagent compound and the best ratio of red: blue was3:7.