The Research On Increasement Of Deinking Efficiency For Recycled-pulp Based On Effective Monitoring Of Stickies In Product-line

This paper points out that all the stickies found in the line are tacky mixtures at 40℃~105℃, which is the temperature range in the line. The key components of the mixtures are organic polymers which from paper chemical additives. The key point of stickies effective governance are controlling the access balance of organic polymer in the line. When the problem of organic polymer accumulation is solved, the attendant problems such as stickies and low deinking efficiency will be solved simultaneously, which are caused by the organic polymers stick to fillers, micro fibers, impurities and ink particles together. This paper demonstrates the relationship between the organic polymer accumulation and stickies operational barrier formation. The former is a prerequisite. The orginic polymer accumulation will be formed when the amount introduced into the line remains above taken away from the line continuously. Flocculation is the direct cause for the formation of stickies operational barrier. Flocculation plays different roles during the process-line. The organic polymers turning into macro particles, which is helpful for the increasement of the impurity removal efficiency before thermal dispersion process, but it brings the stickies operational barriers for blocking the pores in the paper formation felt and adhering the dryer after thermal dispersion process. This paper demonstrates adsorption of pulp and filler on stickies is a physical adsorption process, and there is dynamic balance between adsorption and desorption, by using the typical additives as simulation object, such as PAM which is high molecular weight compound, cationic starch which is charged compound,PVA which is multi-hydroxyl linear compound and rosin which is lipophilic compounds. It analyses the pulp adsorbing capabilities on stickies component in actual pulping process parameters, such as pulp concentration, ash, temperature, pH, agitation or static variable condition, observes the adsorption and flocculation effect of five kinds of typical inorganic adsorbents. It proves that the harm degree of stickies promble from various organic polymers is different in the process, since they have different flooculation value and particle size. So it’s necessary to identify the composition of the organic polymers in order to achieve the effective monitoring of the product-line.It needs the quantitative determination method of corresponding component to monitor the target stickies components in the product-line. This paper focuses on that most stickies key components are high polymer, this characteristic determines that the gas phase or liquid phase chromatographic applications are limited, even they are very effective in quantitative determination in of small molecular weight compounds analysis. It focuses on that the macromolecule organic compound is easy to adhere other impurities, it makes the stickies are mixed highly, this characteristic determines some efficient methods in pure analysis are limited, such as infrared spectroscopy, pyrolysis gas chromatography and mass spectrometry. It focuses on the hydrophilic or lipophilic properties of organic polymer compounds, and proposes that the separation of mixture components is a key point in testing, and puts forward a solution as to choose an effective extraction solvent for lipophilic component, and select a suitable chromogenic agent for water soluble components, the reactants with different colors are quantitatively analyzed by UV spectroscopy. This paper gives the quatitative determination methods of some water soluble compounds, such as starch, PVA, CMC and PAM,and discusses extraction scheme for waste water soluble components of stickies in waste paper. It describes determination method for resin acid compounds contents in paper, and discusses the extraction scheme for lipophilic components of stickies in waste paper. It introduces the determination method for AKD, and discusses the difficulty for analysis of reaction type auxiliary agent in paper products. With above methods, the cause of stickies operational barrier in a newspaper making line was confirmed that by PAM excessive adding in the wet-end process. And the rosin-size retention in some wet-end process was determined. Two SN standards are proposed basing above research. One is SN/T XXXX-2016 Determination of abietic acid in paper and paper products High-performance liquid chromatography method, the other is SN/T 4383-2015 Materials and articles in contact with foodstuffs-Glutinous Rice Paper-Determination of PVA content UV spectrophotometry.Evalvation of deinking efficiency is helpful for improving and perfecting the production process of DIP. It’s necessary to measure brightness、ERIC、dirt(image method) of DIP for comprehensive analysis. This paper drafts a valid method for evaluating the deinking efficiency during DIP product first. It chose sheet-former method to prepare laboratory sheets, and proved with sufficient test datum that preparing 90~100g/m2 sheets with 300~350 mesh wire screen could prevent the micro ink particles lost effectively and pariticle size data distortion like chemical method. The laboratory sheets could meet simultaneously the requirements from brightness, ERIC, dirt test. Further more, this paper gives a pulp-washing scheme to clear the unbounded ink particles using for deinking efficiency determination. One standard QB/T 4896-2015 Determination of deinking efficiency for recycled pulp is proposed basing above research.The deingking efficiency and macro stickies of a hand towel product-line in Dongguan was evaluated according the methods proposed in this paper in May, 2013. It confiremed the internal consumption of deinking effect of the line was serious, and the recycling whitewater had polluted the slurry and reduced the brightness, ERIC. Enterprises upgraded the white water purification system then, removed the stickies in whitewater effectively, and enhance the cleanliness of recycling whitewater by flocculation and precipitation. The deingking efficiency, macro stickies and whitewater cleanliness of the line were determinated again in September, 2015. The detection datum before and after the transformation confirmed fully that the deinking effect of product-line could be improved by effectively by through the effective governance of stickies in whitewater.