Effect of different screening components of APMP on paper properties

APMP pulping maintains the fiber length and softness on the basis of increasing the yield of the pulp, and the pulp strength is good and the opacity is high. However, due to the characteristics of APMP pulping, the length distribution of APMP fiber is not as concentrated as that of chemical pulp. Fibers of different lengths have different effects on the properties of pulp and papermaking. In this experiment, the black poplar APMP with a beating degree of 50°SR was selected as the object of study. The sizing agent was divided into different fiber components by sifting to investigate the different strengths, tightness and opacity of different screening components. Impact.

1 experiment

1.1 Raw materials and equipment

Ingredients: Black poplar APMP was obtained from Hunan Tiger Forest Paper Co., Ltd. and its degree of beating was 50°SR.
Equipment: PFI refiner; ZQJ-BT type pattern sampler (Northwestern Institute of Light Industry Machinery Factory); fiber sifter (Japan Yasuda Seiki Machine); multimedia optical microscope; fiber mass analyzer FQA (OpTest, Canada) .

1.2 Experimental methods

1.2.1 Preparation of slurry
The PFI refiner was used to refine the slurry and the degree of freeness of part of the slurry was increased from 50°SR to 65°SR to compare APMP's impact on paper properties with different screen components at different freeness.

Refining conditions: refining gap of 0.2 mm, refining concentration of 10%, and refining rotation of 8,000 revolutions.

1.2.2 Screening

In the experiment, 28, 48, 100, and 200 mesh screens were used to screen the pulp samples and determine the content of each screening component at different beating degrees.

1.2.3 Observation of Fiber Morphology

The slurries with a beating degree of 50°SR were taken as the objects of observation. The fibers in the different screening components were sampled, made and dyed, and were magnified 100 times and 400 times under a multimedia optical microscope. The morphological characteristics of the fibers were observed and analyzed.

1.2.4 Analysis of Fiber Quality

The morphological parameters of the fibers in each screening component of the pulp with a beating degree of 50°SR were measured by FQA, including the weight average length, the coarseness, the fine fiber content of less than 0.2 mm, and the fiber kink index.

1.2.5 Papermaking

In the experiment, one component was sieved in order, and the remaining components were thoroughly mixed and then paper-making. The quantitative amount of the tablet was 60 g/m2. To ensure sufficient retention of the fine fiber components in the slurry, cationic polyacrylamide (CPAM) and bentonite retention systems were used in the experiment. The amount of CPAM was 0.08%, and the amount of bentonite was 0.2%. After adding CPAM, bentonite was added.

2 Conclusion

2.1 The beating degree of 50°SR black poplar APMP, the content of fiber components retained on the 28-mesh screen was 26.6%, and the content of fiber components between the 28-mesh and 48-mesh screens was 16.4%. The fiber component content between the 48-mesh and 100-mesh screens was 16.7%, the fiber component content between the 100 mesh and 200 mesh screens was 16.8%, and the fiber component content passed through the 200 mesh screen was 23.5. %.

2.2 Observed under a multimedia microscope at a magnification of 400 times, the long and medium long fibers in the APMP pulp did not show a significant deuteration phenomenon as in the conventional chemical pulp fibers. In comparison, the short fibers and the fine fibers were observed. The detangling phenomenon is more obvious.

2.3 From the measurement of fiber morphology parameters, it can be seen that from the long fiber, medium long fiber, short fiber, secondary small fiber to small fiber component, the average fiber length gradually decreases, the thickness gradually increases, less than 0.2mm small fiber content Gradually increase, the kink index does not change much.

2.4 Screening comparison experiments showed that the fiber components passing through the 200-mesh screen had the greatest effect on the tightness and opacity of the paper. The higher the content, the greater the paper strength and the effect on the tensile strength.