How to prevent and solve coated white board in the

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How to prevent and solve the yellowing phenomenon of Coated Whiteboard in the printing of color box packaging box

color boxes used in product packaging, all kinds of commodity packaging use recent packaging boxes, which are mostly made of white cardboard. The newly purchased white cardboard is overcut, Ink "> printing and subsequent processing have become our product packaging boxes.

today, with the increasing emphasis on material enjoyment and consumers' requirements for product quality and price, people have higher and higher requirements for the quality of packaging paperboard (Coated Whiteboard, also known as white paperboard) As a high-grade packaging material, Coated Whiteboard has become the goal of people to pursue its exquisite appearance quality. However, the yellowing of the packaging box during the use of Coated Whiteboard has seriously affected the beauty of the outer packaging materials. Yellowing of Coated Whiteboard refers to the phenomenon that the whiteness of the product will decrease after a certain period of storage or sunlight exposure. Research on the yellowing phenomenon and its mechanism of Coated Whiteboard, find out various factors of yellowing and the measures and methods to stabilize the whiteness have attracted our attention increasingly. This paper mainly analyzes the yellowing phenomenon of Coated Whiteboard Based on production practice, and discusses how to prevent and solve the yellowing phenomenon

1. The latest research results show that the yellowing phenomenon is that the paperboard surface material reacts with oxygen in the air during storage and after sunlight, which changes the chemical structure of the surface material, thus affecting the visual effect of people. The degree of oxidation determines the severity of yellowing. The oxidation process is mainly promoted by the following three factors: ① high temperature, ② ultraviolet light, and ③ pH value

2. Factors affecting the yellowing phenomenon of coated white board

from the analysis of the promoting factors in the oxidation process and the material composition of coated white board, the factors affecting the yellowing phenomenon of coated white board mainly include the following aspects: coated white board base paper, fluorescent brightener, toner pigment, coating adhesive, etc

3. Prevention and solution measures for yellowing of coated white board

3.1. Process adjustment of coated base paper: bleached chemical wood pulp is used as the surface pulp fiber of base paper, and the amount of surface pulp is increased to strengthen the coverage of lining mechanical pulp. The medium alkaline sizing process is adopted to reduce the amount of aluminum sulfate in the face pulp and improve the 13h value of the base paper. It is proved by experiments that the pH value of the base paper surface is between 6.5 and 8.0, which has a good effect. In the process of papermaking, the drying temperature should be strictly controlled to ensure that when the paperboard is dry, the drying temperature should be reduced as far as possible, and the cold cylinder of base paper and coated paper should be used well

3.2. Choose liquid brightener with good quality: experiments have proved that the application of liquid brightener can reduce the yellowing degree of coated products. While ensuring to improve the self-sufficiency of the product, its effect on yellowing is significantly lower than that of powdered brightener. The liquid brightener with good quality must have high purity. Liquid brighteners with poor purity will not only cause unnecessary waste, but also easily form yellowing. In addition, the fluorescent brightener should be used well in the paint formula, and the application of brightener carrier (auxiliary adhesive) should also be paid attention to

3.3. Rational application of tinting pigments: the use of tinting pigments is to maximize whiteness (CIE), reduce the amount of fluorescent brighteners, and balance different chemical raw materials to achieve the desired hue. In order to reduce the yellowing of Coated Whiteboard, the selection of color matching pigments requires not only easy operation, good affinity, but also high sun fastness. Therefore, it is best to choose high-quality organic pigments, whose performance in all aspects is relatively ideal. More attention should be paid to the amount of color pigments, because too high or too low amount can not achieve the purpose of color matching. Too high, it will aggravate the yellowing degree of Coated Whiteboard; If it is too low, the required appropriate whiteness cannot be achieved

3.4. Choose a reasonable proportion of coating adhesive Jinan assaying bearing fatigue life testing machine: introduce support policies in the coating formula, in order to prevent and solve the yellowing phenomenon of Coated Whiteboard, under the requirements of balancing the formula cost and product performance, it is almost impossible to use a single styrene butadiene latex as the coating adhesive. Therefore, according to the product performance requirements, styrene butadiene latex can be mixed with other latex, such as cheap styrene acrylic latex, which can not only ensure the strength performance of Coated Whiteboard, but also reduce its yellowing degree

3.5. Selection of new chemical additives: the author found that nano silicon based oxide has obvious potential in reducing coating yellow due to its unique molecular structure. In the eye aging test, the absolute value of chromaticity b value decreases very little. In addition, UV absorbers and antioxidants can also reduce the yellowing of the whiteboard coating

3.6. Other factors that should be paid attention to: for example, the pH value of coating, the purification of coating water, the use of coated starch, the moisture of coated paperboard, the packaging and storage of coated paperboard, etc. Although these are not the main reasons for yellowing, as long as the prevention is strengthened in all aspects, it is also very effective to solve the yellowing of Coated Whiteboard

4. Conclusion

4 l. In the production practice of solving the yellowing problem of coated white board, coating base paper, fluorescent brightener, tinting pigment and adhesive are the main factors affecting the yellowing. Improve the process conditions of base paper production, select high-quality fluorescent brighteners and color pigments, and adjust the optimal dosage; Scientific determination of the best combination of adhesives can effectively reduce the yellowing of Coated Whiteboard

4.2. The use of new chemical additives, such as nano silicon-based oxides, UV absorbers and antioxidants, will also reduce the yellowing of Coated Whiteboard

4.3. Strengthening the production control of coated white board and the prevention of packaging and storage conditions is also a beneficial way to solve the yellowing of coated white board

all the involved processes are controlled, and the operation is standardized and process oriented. Then our coated white cardboard is also of first-class quality. Of course, the produced packaging boxes and color boxes are also first-class. These shy people work together

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