Pilot production of the hottest light weight coate

Trial production of light weight coated paper (VI)

2.5.2 some problems in the maintenance of soft roller calender

German experts have very strict requirements for this soft roller calender with high technical content. From the date of entering the factory, each calender roll should establish its own storage and operation files. For example, the rollers stored in the warehouse should regularly record the ambient temperature, humidity, ventilation, roller placement Whether the covering protection lignin/polyethylene (PE) is intact, etc. After the roller is put into operation, it is necessary to record the operating conditions, maintenance conditions and changes of the roller in a more detailed and timely manner. However, what we have actually achieved is not even one third of the requirements of German experts. Our soft calender actually operates under unsafe conditions. In the early stage, many hard particles and sands were embedded in the elastic coating of the soft roll of the calender, and the whole flat and smooth roll surface was damaged. Then there was a major accident that the soft roll coating suddenly cracked in a huge sound during operation. These accidents tell us that we must attach great importance to the use, maintenance and care of soft calender

with this kind of expansion, hard particles, sand and other hard objects embedded in the elastic coating of soft calender mostly come from poorly purified slurry and coating, and foreign debris pollution production process is also one of the sources of hard particles. Once these hard spots are embedded in the soft calender, they will not fall off automatically, and it is difficult to peel them out even if they are manually stripped after parking, resulting in the accumulation of hard particles in the soft calendering coating, and finally the whole soft roll surface is damaged. The soft roll must be grinded again before effective calendering can continue

figure 8 metering scraper of coater Working state diagram of overflow scraper

1-metering scraper 2-overflow scraper 3-coating roller 4-coating feeding tank 5-coating collecting pipe

Figure 9 coating flow diagram

1-pigment dispersion storage tank screen 2-behind the screen pigment dispersion storage tank screen 3-coating solution storage tank screen 4-starch gelatinization solution storage tank screen 5-coating filter screen 6-after the filter coating storage tank screen 7-pigment dispersion tank (coating mixing tank) 8-vibrating circular screen 9-starch gelatinization tank

3 main papermaking process and paper quality index of LWC paper

3.1 main papermaking process

(1) speed of paper machine: 260m/min; Net paper width: 2640mm

(2) pulse attenuator: air cushion pressure 0.013 ~ 0.015MPa; The return flow of slurry shall not be less than 3% of the total slurry

(3) part

① headbox: slurry velocity ratio 0.995:1; Lip opening height 10.85mm (actual 10.295mm); The opening width of the lip is 2970mm; The opening difference of lip plate should be ≯ 0.2mm; The slurry concentration is 0.6% - 0.7%; The slurry return flow shall be maintained at 10% of the total slurry feed

② vacuum degree of low pressure differential suction tank: -

③ vacuum degree of upper water collecting tank: ＃ 1 0.01Mpa 2 0.05MPa。

④ vacuum degree of high pressure differential suction tank: ＃ 1 0.002mpa 2 0.003MPa；＃ 3 5. Start the beam motor 0.005MPa 4 0.008MPa；＃ 5 0.012MPa；＃ 6～＃8 0。

⑤ vacuum degree of vacuum couch roll: 0.05Mpa in chamber I; Chamber II 0.07MPa

⑥ select electrohydraulic servo universal experimental machine for upper cutting, and the distance between water needles is 2840mm

⑦ water line position: disappear on 4 high pressure differential vacuum box

⑧ moisture content of wet sheet exit couch roll: 79.4% - 80.0%

tension during operation of ⑨ part: both top and bottom are 4.5 ~ 5.5kn/m. (to be continued)