| dc.description.abstract | Since the coming out of digital camera and the popularizing of cell phone camera, the number of photos developed by traditional film has dropped rapidly, but the quantity of digital image printing derived by digital camera and cell phone camera has been climbing up over years. Among the technologies of digital image printing, thermal transfer printing technology has the advantages of high resolution, high printing speed, waterproof (with the design of protective layer), hue continuity, natural and real color, etc., and thus is the most promising printing technology in the future market for image output.
Operation mechanism of thermal transfer printer: use micro heating piece on the heating head of the printer to heat the back side of dye ribbon, so that the dyestuff on the dye layer of the front side can be transferred onto thermal transferable paper to make high quality photo.
When manufacturing thermal transferable paper, cutting edges, waste paper during testing, machine startup, and equipment disorder can become source of waste material. Because thermal transferable paper belongs to composite material, coated with plastic material like OPP and PE, so it is hard to be recycled and reused. Therefore, domestic recycling organizations are not willing to collect the remnants of thermal transferable paper. Consequently, the remnants of thermal transferable paper, treated as ordinary unrecyclable waste, can only be sent to incinerator. This leads to a waste of manufacturer′s money and costs, and what′s more, the process of incineration consumes energy and brings environmental pollution. In this research, we hope to find out a way to recycle the remnants of thermal transferable paper through experiment and verification procedures, so as to break through the bottleneck of recycling thermal transferable paper remnants and make full use of the value of the remnants.
This study takes hydrapulper of Tetra Pak as a reference to conduct tests in three phases. The first phase used a blender instead of a pulper to conduct a preliminary experiment. The pulping results show that the matte OPP, white glossy WBOPP and PE plastics are in a floating state in the pulp and that they are separated from the paper pulp fiber and then collected to be used for the subsequent recycling process.
The second phase used a standard pulper to conduct the pulping experiment. In this experiment, it is confirmed that the white glossy WBOPP and matte OPP can be collected in full to be put in re-use. 97% of PE plastic is collected in the mesh screen of MESH 16 which can be put in the subsequent recycling process. The benign paper pulps smaller than MESH 16 is to go through a hand sheet experiment to ensure its tensile strength meeting the conditions of CNS paper, and that it can be used for making recycled paper.
The third phase, under the conditions of no pH value adjustment by acid and alkali and no enzymes or chemicals added, uses the control variables in the cutting sizes of photographic papers, the soaking time of pulp, the pulping time of paper pulp and soaking temperature of paper pulp to conduct hydrapulping experiment with a pulper. This is to confirm the impacts of pulping results and the separation between paper pulp and plastics on the efficiency of recycling without adding any agents.
In the third phase, the experiment of the first group takes the size of photographic paper as the control variable. The study finds that, as OPP, WBOPP and PE can almost all be separated and collected, the size of the photographic paper shows no significance on the recycling efficiency of plastics but has significance on the recycling rate of good pulp. It can be confirmed that the smaller the size of photographic paper, the better effect of pulping. On the contrary, the larger the size of photographic paper, the worse the effect of pulping is.
In the third phase, the experiment of the second group takes the soaking time of photographic paper as the control variable. The study finds that, as OPP, WBOPP and PE can almost all be separated and collected, the wetting time of the photographic paper shows no significance on the recycling efficiency of plastics but has significance on the recycling rate of good pulp. It can be confirmed that the longer wetting time of paper, the better effect of pulping. On the contrary, the shorter the wetting time of photographic paper, the worse the effect of pulping is.
In the third phase, the experiment of the third group takes the pulping time of photographic paper as the control variable. The study finds that, as OPP, WBOPP and PE can almost all be separated and collected, the pulping time of the photographic paper shows no significance on the recycling efficiency of plastics but has significance on the recycling rate of good pulp. It can be confirmed that the longer pulping time of paper, the better effect of pulping. On the contrary, the shorter the pulping time of photographic paper, the worse the effect of pulping is.
In the third phase, the experiment of the third group takes the soaking temperature of photographic paper as the control variable. The study finds that, as OPP, WBOPP and PE can almost all be separated and collected, the soaking temperature of the photographic paper shows no significance on the recycling efficiency of plastics but has significance on the recycling rate of good pulp. It can be confirmed that the higher soaking temperature of paper, the better effect of pulping. On the contrary, the lower the soaking temperature of photographic paper, the worse the effect of pulping is.
From the literature review we can learn that the recycling rate of Tetra Pak paper pulp fiber is approximately 30% to 37%. However for dye-sublimation photographic papers under the same type of hydrapulping technology, no matter what the control variables are in terms of the sizes, soaking time, pulping time and soaking time of the photographic paper, the recycling rate of paper pulp fiber can reach as high as 39.13% to 39.85%, apparently higher than the recycling rate of Tetra Pak paper fiber.
Summarizing the above, it is experimentally proven that the ingredients of photographic paper can be separated into matte OPP, white glossy WBOPP, PE plastics and paper pulp. The handsheet experiment demonstrates that the paper pulp from photographic paper can be re-manufactured into handsheet. Separation of plastics and the collection rate of paper pulp can be changed under different control variables. Reducing the size, increasing the soaking and hydrapulping time and increasing the soaking temperature all can be beneficial to the results of plastics separation and the recycling rate of paper pulp.
By summarizing experiment results, we prove that thermal transferable paper is recyclable and reusable. The relevant operation parameters can serve as a reference for environment protection industry and paper recycling industry.
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