Discussion on the most popular microcapsule techno

2022-07-25
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Discussion on microcapsule technology and silk printing (V)

3.11 printing of sanitary products for daily use. For example, the fragrance microcapsules mentioned above can be widely used in ribbons, handkerchiefs, scarves, toothpastes, ties, curtains and other articles in daily necessities. For example, microcapsules containing polyvinylpyrrolidone iodine complex bactericide use polyester as the wall material, which has strong bactericidal ability and can be used in durable sanitary and antibacterial printing materials; Microcapsules containing certain chemical substances with medical effects can also be made, which can be firmly fixed on rijiao products and released in people's daily use, playing a therapeutic and health care role for people; Another example is that microcapsules of moth proofing agents can protect high-grade books, fabrics and wood from moths

3.12 other printed matter

(1) used for label pasting: Micro balloon capsules are coated on the surface of the adhesive film to ensure that the adhesive will not stick before pressurization. Only when the micro balloon breaks under pressure and the adhesive surface is directly exposed can the article be bonded. (2) Making low density paper: when the paper is made by mixing the pulp with the micro balloon capsule and adding the synthetic resin adhesive lotion, the density is reduced, but the paper strength is not reduced, and the price of the paper is cheaper. (3) Application in flame retardant packaging and printing materials: flame retardants are often used in building materials, plastics, textiles, papermaking and other industries, such as phosphorus containing flame retardants, which can form a layer of molten polyphosphate film on the surface of the object during heating, and isolate the object from oxygen and flame, so as to extinguish the flame. For example, red phosphorus is a kind of flame retardant with low price, less dosage and less smoke. However, like other flame retardants, it is easily affected by water, oxygen and other chemicals in the surrounding environment, sensitive to heat, friction and impact, poor compatibility with plastic substrate, easy to precipitate and affect its performance. Therefore, it is necessary to make microcapsules before use to make them be applied in practice. Although they have also developed various small panel control systems

4 Microcapsule silk printing process

because the particle size of microcapsule is about 2 ~ 200 μ M, which is thicker than the general printing ink layer, so the printing method should be selected. Generally, silk printing can fully adapt to the characteristics of microcapsule ink transfer. Because silk printing has some advantages, for example, the printing ink layer is thick, up to 100 ~ 300 μ M, which is thicker than the microcapsule particles, can not only protect the microcapsule, but also obtain the printing effect that other printing methods can not achieve; In addition, silk printing can be suitable for substrates with different materials and shapes, which lays a foundation for the wide application of microcapsule technology

the following problems should be paid attention to in microcapsule printing

① wire selection: in order to ensure the quality of wire printing without causing damage to microcapsules during printing, the relationship between the width of wire holes and the volume of microcapsule particles in the ink should be clear when selecting the number of wire mesh. Generally, the width of wire holes is at least 3 ~ 4 times the diameter of microcapsule (or filler) particles in the ink. In addition, attention should be paid to the braiding form of silk, and monofilament plain woven silk should be used

② plate making: the plate making method of the general microcapsule printing picture is not much different from that of the ordinary printed matter, but try not to select the picture with very rich original levels and high definition requirements as the original, because the ink containing rich microcapsule particles is difficult to show the color and level of the picture

③ ink viscosity: there are also requirements for ink viscosity. If the viscosity is too high, the ink is not easy to transfer to the substrate through the silk plate, resulting in printing difficulties; If the viscosity is too low, it will enlarge the imprint, affect the printing quality, and even cause waste products. Before printing, the viscosity of the ink containing microcapsules shall be adjusted so that the weight of the installation equipment will cause vibration and have a certain viscosity. The diluent shall be appropriate so that the microcapsule particles can be smoothly penetrated without affecting its quality

④ printing speed: the printing speed should not be too fast in the printing process, so as to avoid the temperature rise caused by the friction of the doctor blade, which will lead to the rupture of the microcapsule particles. At the same time, the rheological properties of the ink should also be considered

⑤ printing pressure: in order to ensure that the ink can be transferred to the substrate smoothly through the silk hole, the adjustment of printing pressure is very important. In addition to paying attention to whether the ink on the layout is uniform after scraping, the microcapsules should also be observed to avoid damage without cracking. For microcapsules with different wall materials, different printing pressures should be applied in combination with the printing effect

⑥ arrangement of printing color sequence: when multiple sets of overprinting are carried out, specific arrangement shall be made in combination with the actual situation. Since not every color contains microcapsule particles, the color sequence position of the color ink with microcapsule particles shall be reasonably arranged. If the microcapsule color ink is placed in the last color for printing, the microcapsule body can be avoided from being damaged during subsequent printing; However, when it is printed on the front, it can also protect the release of microcapsules because the ink is superimposed later. Therefore, it should be reasonably arranged in combination with the actual situation

⑦ drying method: some microcapsules will break under light irradiation or heat. Therefore, in combination with specific microcapsule characteristics, select the required drying method. Let me tell you the application of universal tensile testing machine in the automotive industry: infrared drying, volatile drying, UV (ultraviolet) light solid drying and other methods

in a word, when printing the ink containing microcapsule particles, it is necessary to prevent the microcapsule from cracking and premature release during the printing process, and to fully improve the quality of the printed matter. Therefore, it is necessary to carry out experiments and print in large quantities after mastering some experience

Author: Qian Junhao source: silk printing

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