[China Packaging News] The quality requirements of DIP used in the production of high-end cultural paper are high, especially the relatively high whiteness requirements, and more importantly, there are fewer stickies and dust spots. The production practice of Yue paper shows that when DIP is used for high-end cultural printing paper with a whiteness exceeding 90 % ISO and a dosage exceeding 40% , the whiteness (non-fluorescence) of DIP should be greater than 75% ISO and the dustiness should be less than 100mm2 / kg The stickies should be less than 100mm2 / kg , and the ERIC (total ink content) should be less than 100mg / kg (ppm) . If copy whiteness is greater than 98 % ISO copy paper products, DIP whiteness (non-fluorescent) should be greater than 82% ISO , dustiness should be less than 50mm2 / kg , adhesive should be less than 50mm2 / kg , ERIC should be less than 50mg / kg (ppm) .
In the production of high-end cultural paper, in order to ensure the quality of DIP , we must start from the key technologies of waste paper raw material ratio, deinking process, thermal dispersion process, flotation process, screening purification process, bleaching and reuse water treatment and other key technologies.
1. Process selection
The quality requirements of DIP pulp for the production of high-end cultural paper are high. Therefore, the process design is very different from the DIP production line for newsprint . In order to ensure the quality of the pulp, three levels and four stages of slag removal are selected. , Three-stage four-stage screening, three-stage two-stage flotation, two-stage heat dispersion, one-stage H2O2 float, one-stage reduction float.
After being selected, the waste paper is sent to the drum pulper through the chain conveyor to be crushed, and then pumped to the high-concentration slag remover to remove coarse impurities such as sand, fiber bundles, iron, etc. Then enter the medium-concentration screening to remove the sticky matter contained in the slurry, and then remove the fine sand particles mixed in the slurry through the low-concentration sand remover. The purified slurry enters the first flotation deinking, and then the fine screen In screening, most of the stickies are removed in the fine screening stage. The screened slurry is washed and concentrated in multiple trays and then goes to the screw press and # 1 heat dispersion system. Then the slurry is sent to the second flotation. After flotation, it is further purified by the sand removal system. The purified slurry is washed and concentrated by multiple discs, and then processed by the spiral squeezing and heat dispersion system, so that a higher Production yield.
The slurry obtained from the # 2 heat dispersion system is bleached with H2O2 at a concentration of 25%-30% . After bleaching, the slurry undergoes a third flotation deinking and is washed and concentrated by a multi-disc concentrator. It is sent to the reduction bleaching tower for reduction and bleaching. After the slurry is processed, it is sent to the pulp tower for storage, and then sent to the papermaking workshop for the use of the slurry.
2. Ratio of waste paper
The types of waste paper are different, and the types of inks, fibers, and qualities used vary greatly. The original design of Yue paper's 550t / d DIP production line used more than 70 % of mixed office waste paper, but due to the double constraints of the market and the price of waste paper and the affordability of DIP pulping costs Comprehensive research and analysis of ash, fiber sieving, fiber components, deinking process, flotation, bleaching whiteness value increase, residual ink content and pulp yield, cost performance, etc., and simultaneously conduct a variety of waste paper ratio test Research, and gradually find a more economical waste paper ratio that can meet the DIP quality requirements.
The research results show that: among the several kinds of waste paper used in the production of culture paper pulp, domestic coated paper and # 10 waste paper have the highest cost performance, and they should be matched as much as possible. When the whiteness of the deinked pulp is not very high, some # 8 waste paper can be used to reduce the cost of the pulp, and as little or no # 37 waste paper and domestic office waste paper as possible. Procurement of imported chemical waste paper or imported coated waste paper with a high proportion of chemical pulp (price slightly higher than # 10 waste paper), replacing part of # 37 waste paper, to solve the problem of high price and insufficient supply of # 37 waste paper.
3. Quality control of waste paper
The 550t / d DIP production line of Yuezhi Paper is equipped with a bulk packer and sorting belt. However, the thickness and speed of the waste paper stack and the length of the sorting belt after the bulk packer packs into the sorting belt seriously affect the effect of waste paper sorting. , Light and heavy impurities, forbidden objects, discarded objects, and non-similar waste paper are difficult to sort, making DIP dust difficult to reach the standard for a long time, especially yellow cardboard, envelopes and other natural fibers cannot be effectively sorted out. The amount of offset paper that has been copied becomes a waste due to yellow dust, which seriously affects the economic benefits of the enterprise.
In order to strengthen the sorting, the company has set up a screening system for waste paper bulk drying method. The system is to fully pack the packed waste paper bundle into sheets, which facilitates the sorting and sorting of waste paper, and at the same time effectively removes light and heavy impurities by dry method. The system can control the thickness and speed of the waste paper stack of the sorting belt, and the length of the sorting belt is long. Many people stand on both sides of the sorting belt to manually sort, especially forbidden objects, discarded objects, and those containing natural fibers Basically, waste paper can be effectively picked out. During the production, the amount of waste paper that was fully sorted was increased, and the quality of DIP was improved.
4. Selection of deinking agent
In today's mixed office waste paper, ultraviolet ink, laser printing ink, flexographic printing ink and other new inks account for a considerable amount. Copying high-end cultural paper is a mixture of various waste paper in a certain proportion, which makes the deinking more difficult.
From the research results: the higher the proportion of printing waste paper such as # 10 waste paper, # 8 waste paper and coated paper in the waste paper ratio, the better the comprehensive performance of anionic surfactants such as sodium soap deinking agent, office The higher the proportion of waste paper, the more dominant the non-ionic surfactant. The ideal situation is that the two ionic types are compounded. The key is that the working conditions and control parameters of products from different suppliers are different, and need to be adjusted in production according to the actual situation.
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