Application of SWP Fiber in Colored Paper

Colored paper is a special type of artistic paper made by mixing bleached chemical wood pulp and SWP pulp. It has rich colors, flat and wide paper, and has the unique characteristic of changing color after hot stamping. Its main principle of use is to use engraved copper or zinc pattern plates, and heat stamp the surface of the paper with a hot stamping machine to reach a temperature above the melting temperature of SWP pulp. In the hot stamping part, the SWP fibers inside the paper melt, and the color darkens accordingly. The paper surface shows concave or convex dark pattern prints and text prints, which demonstrate the effect of printing and stamping. After hot pressing, the pattern has distinct layers and strong three-dimensional sense, giving people a sense of nobility and elegance. This type of paper is mainly used for packaging high-end products, such as gift box packaging, high-end wine box packaging, best-selling book covers, greeting cards, decorative paintings, etc. Its color changing characteristics after hot stamping mainly come from SWP fibers.

The properties and mechanism of action of SWP slurry

SWP pulp is a polyolefin, multi branched chemical fiber that has undergone hydrophilic treatment and has good water dispersibility. It can be well mixed with various synthetic fibers and plant fiber pulp and can be made on ordinary long and circular mesh paper machines. The spectra of SWP pulp fibers and coniferous wood pulp fibers are shown in Figure 1.

Its main characteristics are as follows:

(1) The inherent variability of SWP pulp fibers results in a high specific surface area, enabling effective capture of fine fibers during the papermaking process and improving pulp retention.

(2) The polyolefin properties of the fibers themselves make the mixed slurry have good dehydration and drying performance.

(3) The shape and size distribution of SWP pulp fibers are similar to those of ordinary wood pulp after fine grinding, so SWP pulp does not require fine grinding. Fine grinding or pulping of SWP pulp will only reduce fiber length and damage papermaking performance.

(4) The ZETA potential of SWP pulp exhibits strong negativity, with a ZETA potential of approximately -36mV, while the ZETA potential of wood pulp is generally around -25mV. According to the principle of mutual repulsion of same-sex charges, SWP pulp has good dispersibility with wood pulp fibers during the papermaking process, making it less prone to flocculation, thus improving the uniformity of the paper and enhancing its papermaking performance.

(5) SWP pulp fibers have a low melting point, generally between 100-135 ℃. Paper products made by mixing SWP fibers are prone to embossing and deep extrusion processing, and can exhibit a more three-dimensional design compared to ordinary paper products.

Given the above characteristics of SWP pulp, it can be widely used in the paper industry. By utilizing its low melting point and embossing adaptability, it can be applied to color paper and its application effect should be paid attention to.

Selection of 2 SWP slurries

SWP pulp can be processed into many grades based on fiber length, freeness, melting point, and moisture content. It is necessary to select the appropriate grade for paper production according to the quality requirements of the finished paper. The basis weight of colored paper is 60-100g/m2, requiring good paper uniformity and certain mechanical strength to meet the needs of embossing processing. Therefore, A and B grades of synthetic fibers are selected to be used in combination to meet the above quality requirements.

SWP-A fiber has a length of 0.9mm, a free degree of 580ml, an absolute dry moisture content of 63%, a melting point of 135 ℃, and gives the paper good uniformity; SWP-B fiber has a length of 1.2mm, a free degree of 340ml, an absolute dry moisture content of 64%, a melting point of 135 ℃, and gives the paper good fiber bonding strength.