Discussion on the printing technology of the hotte

2022-07-28
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Discussion on paper cup printing technology (Part 2)

2. composition of paper cup paper

paper cup paper is extruded and compounded from paper cup base paper and plastic resin particles. Plastic resin is generally used as plastic resin. The paper cup base paper is coated with single-sided PL film or double-sided team film. Become single PE cup paper or double PL cup paper

pe is nontoxic. Odorless, odorless, tasteless, sanitary, reliable, stable chemical performance, balanced physical and mechanical properties, good cold resistance, water and moisture resistance, certain oxygen resistance, oil resistance, excellent molding performance and good heat sealing performance. The team has large production capacity, convenient source and low price, but it is not suitable for high-temperature cooking. If there are special performance requirements for paper cups, resin with corresponding performance should be selected for coating

printability of paper cup materials

1. surface requirements of paper cup base paper

direct printing paper cup base paper shall have certain surface strength {wax stick value ≥ 14a) to prevent hair and powder from falling out during any printing. At the same time, the base paper of the paper cup must have good surface fineness to ensure uniform inking of the printed matter.

2. surface treatment before printing

the surface of the base paper or base film to be printed must be clean. It is dry, flat and free of dust and oil. For non-polar PE and other structures with dense and smooth surface, its surface tension value is only 2 days ~ 31mn/m Before this printing, corona treatment is required to change the surface state. The surface tension value should be increased to 40Mn/M and at least 38mn/m. That's the only way. Printing ink can reach certain adhesion fastness on the surface of substrate

after corona treatment of double-sided composite paper, the treatment effect of PE film will fade exponentially with the extension of storage time. The speed of fading is related to the temperature of storage environment, raw material brand, film thickness and other factors. The higher the storage temperature, the slower and more thorough the fading speed. For example, when the film is stored in an environment below 20 ℃, the critical surface tension of the film is 30-42mn/m, which can be maintained for one month or even half a year. However, when the ambient temperature is above 36 ℃, regardless of the degree of treatment of the original film, the surface tension of the material will subside to below 38mn/m after one month of storage. Generally speaking, the surface tension of thick films dissipates faster than that of thin films. Therefore, it is best to print the materials immediately after corona treatment to obtain the best wettability and adhesion

paper cup printing process

1 ink

heat sealing performance required for continuous forming of paper cup and printing suitability of PC film surface. It is required that the ink composition, residual solvent, drying conditions and other factors must be compatible with the performance of the paper cup

the poor quality of paper cup printed matter is the result of the reasonable combination of printing machinery, printing process substrate and ink. As long as one of them is not well matched, the printing quality of the paper cup will be affected or the printing process will fail

flexible water-based ink is usually used for cup paper printing. For water-based ink. The adhesion of ink is very important. In order to avoid loss, a large number of tests should be done before formal printing in order to select the ink with good adhesion. Only by selecting the appropriate ink can the printing products obtain good light resistance, heat resistance, friction resistance and other properties

therefore, the ink used for paper cup printing requires good adhesion and good acid resistance on the surface of the printed matter. Alkali resistance, water resistance, heat resistance and light resistance will not fade due to the action of external factors such as acid and alkali. Discoloration, ink layer falling off, etc. In addition. Paper cup printing products should have good scratch resistance, gloss, semi extinction and extinction

the components of the ink must comply with the food hygiene law and the corresponding food packaging hygiene standards

2. solvent

the selected ink solvent shall not make the team film swell as much as possible, and the solvent shall not contain water to prevent the printed matter from curling. The ink containing plasticized free carrier shall be selected as far as possible to prevent different shrinkage of ink film and PE film due to temperature change, resulting in curling of printed matter. The curled printed matter will be warped after being cut into fan-shaped pieces, which will bring difficulties to the conveying of cup making and the curling forming process based on the existing industrial foundation of the park

the amount of residual solvent should be less to prevent the paper cup from generating odor after printing, and the back of the printed matter should be rubbed and dirty. The solvent adheres to the base material or base film at the sealing place, which will cause poor thermal sealing, poor bonding or poor solid bonding at the sealing place, and curling and bursting

3. drying temperature

after printing. The drying temperature of the printed matter shall not be too high. When the temperature is too high, the surface of the base film will produce peroxidation reaction, resulting in poor heat sealing. However, it is also necessary to prevent the printing ink from drying the product, so as to avoid the paper cup from producing odor

4. temperature and humidity of the environment

the relative humidity of the workshop is too high. It will also cause the printed matter to curl. The printed roll film will adhere between the upper and lower films in the environment of high temperature, which will also affect the subsequent paper cup processing and forming

author/Zhenjiang Dadong Paper Co., Ltd. liucunfen, tanninghua, zhuliping

information source: printing technology 2005/9

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